1. Because the average American believes speed limits aren’t meant for the especially skilled drivers like themselves.

2. If the speed limit is raised, then people will drive 10-15 MPH over the new limit. Natch.

3. Traffic enforcement cameras have been routinely abused by the government and so have to be regularly taken away from them like the naughty children they are.

4. People will assure you that civil planning has done their job and everything is already working like a well-oiled machine. I don’t know why people keep saying this when it’s obviously not true. It’s astounding.

3. Why is traffic enforcement given to very expensive and ineffective police instead of cheaper and more automated traffic cameras?

Fuck. Off. With. Your. Surveillance. State. Bullshit.

Speed limits are designed for suboptimal road conditions. Since dynamic speed limits weren’t even possible until relatively recently, they figured out how quick you could safely travel on a road when it is nice, and again when it’s crappy, and set it somewhere between those values.

85th Percentile Rule (where applicable): In many states, a common engineering principle is to set the speed limit near the speed at which the majority of drivers travel under free-flow conditions. Some states adapt or supplement this approach with safety-oriented judgments.

https://thelegalguide.org/who-decides-speed-limits-federal-state-local-roads/

I think the dissonance about speed limits is why there are so many awful drivers, at least in my neck of the woods. You go through drivers ed and you’re trained to go exactly the speed limit in all circumstances, and then you get let loose and find out on some highways, driving under the speed limit is so slow compared to the actual rate of traffic that doing so would be dangerous. People learn that and figure that all of the rules of the road are stupid and bad and you have a country of awful drivers

it doesn’t help that, as another commenter mentioned, you can be ticketed for not moving with the flow of traffic. follow the law, and you’re still breaking the law! plus all the asshole drivers who will get right up on your rear bumper if they decide you aren’t going fast enough. damned if you do, damned if you don’t! although ultimately, going slower is almost always the better choice from a safety standpoint because of that whole “physics” thing

And, yes, I know there’s some thing people did long ago to set the speed limit at some percentile of what people were already traveling at, but that’s obviously a stupid way to do it and we did it anyway. So why?

I’m going to disagree about that being a stupid way to do it, for two reasons.

First, there was a time traffic engineering was not a well-developed field. There was no expert who could combine science and best practices to get a good answer about how fast it’s safe to drive on a particular road because humanity had not yet learned that skill. Measuring what most drivers do, then reducing it if people crash a lot in a particular place is far from the worst approach.

Second, it’s bad to make laws that most people will only obey with heavy enforcement. It’s bad for a society to make lawbreakers out of most of its members, and to create pretexts for police to stop people without other evidence of wrongdoing. If there’s a reason to make most people drive a particular road much slower than they actually do, any reduction in speed limit should also be accompanied by changes to the road design (traffic calming).

It’s one of those areas where we want to regulate something we don’t really want to, so we’re stuck at a compromise that nobody says they are happy with but also nobody wants to change.

We set speed limits (so we did something about traffic deaths), but we don’t enforce them, because drivers would hate that. The upside of the existence of speed limits is that reckless drivers can be charged with speeding if they cause an accident. The downside is that police departments make a revenue stream of ticketing citizens driving at completely safe and reasonable speeds.

Some parts of Europe have automated average speed cameras. That’s way more draconian than a speed camera: they take a pic at each checkpoint, they know the distances between them, if your time is better than what you could do by driving at speed limit, you get a ticket. I would go nuts if I had to drive like that. It would work for autonomous vehicles, so I expect that systematic speed limit enforcement will coincide with the rollout of autonomous cars, which will be the time to stop driving on public roads anyway.

Another similar area is immigration, sorry for the off topic tangent, but I think it’s a similar dynamic. Anti immigration politicians say they want to make tough laws that keep immigrants out, but the laws are not enforced, because without immigrants entire sectors of the economy would stop working. Progressive politicians say they want lax laws so everyone is welcome to enter, but that would be a shitty law because you can’t run a country without borders. So the likelihood that we end up with regulations that allow the right amount of migrant workers and respect refugee rights, and then are actually enforced, is about zero.

Wealth inequality is so outrageous. I sometimes have to cross a 4 lane road to get to an official bus stop. I mean, they built a fucking bus stop, and the fucking bus stops there multiple times a day, they have to assume people are crossing the street at least once. Signage? None. If I get hit, it’s my fault. I sometimes have to wait a few minutes at rush hour for a safe time, and thank god there’s a generous median or I’d be just standing in traffic doing hailmary’s just to get home.

But I live right near a lake and when those rich fucks want to cross the lakeside road to go from their mansions to their private beach there is a fuckton of signage:

WARNING: CROSSWALK AHEAD

SLOW

CROSSWALK AHEAD

STOP SIGN

BLINKING RED LIGHT

CROSSWALK

And that’s when they actually WALK to the beach because most of the time they’re taking their little private golf carts.

I understand why the French Revolution went the way it did.

I find it frustrating that in the US at least, people can’t do the simple math. Unless it’s a very long trip, speeding doesn’t save you very much time at all. A couple of minutes at the most for a typical commute.

On countless occasions I’ve seen some some reckless moron nearly take other vehicles’ bumpers off to ‘get around’ traffic. And then you’re right behind that same moron at the next red light.

They are risking everything for little to no time savings.

Genuine answers from what I’ve heard regarding laws at least in CA:

1. There is a precedent that you should be going with the flow of traffic, which is technically safer than going the speed limit when everyone else is faster-- but mostly only on freeways; I rarely the flow going that fast on streets, so the rule doesn’t apply to that one jackass going 60 in a 40 zone. And yes, you’ll just get to the red faster (good cities time popular traffic lights to the speed limit so it’s even stupider to speed).

2. I’m pretty sure they also set the limit to what older vehicles can pull off safely (assuming you don’t tailgate, anyway). They have upped the limit in some areas, however, which I found upsetting. Like, 70mph up from 55mph over a few decades, which feels fast.

3. Traffic cameras are used, but there’s an interesting issue on legality. If you don’t acknowledge them, they can’t actually say you got the ticket (they come in the mail). I forget the details, but something about seeing your accuser? LA itself more or less decriminalized them, but your mileage may vary based on local government.

4. Places do, in the form of speed bumps, stop signs and curved roads. Not using those is probably more a mix of old roads and poverty-- new suburbs use windy, wide roads. Wealthy neighborhoods install speed bumps and add tons of stop signs. I don’t see it in my neighborhood because “it’ll hurt business” which feels like code for “you don’t matter enough for safety,” hence I think it’s a wealth inequality issue like most things in this country.

Anyway, that’s the best of my knowledge as a CA resident. Honestly, the bigger danger to me are people who tailgate, road rage, drive on sidewalks, and do stupid things to get to an offramp. That last one? Just last Wednesday I saw a guy, car totaled, who tried to hit an offramp they missed by sharp turning into it, going up a 55 degree slope, and getting t-boned by another guy going up the normal way.

Idiots, I swear…

Cops want it that way.

In the USA, you can follow the average driver on a 10 minute drive and they’ll technically commit at least 1 infraction. My FIL got a $90 ticket last month for not coming to a complete stop at a stop sign.

The rules of the road are so anally technical so that cops have a valid reason to pull you over whenever they desire. That’s it.

The short answer to all your questions is that America specializes in stupid in all kinds of ways. This is one of them.

In Canada, its kph, but theres a sign when entering Ontario from Manitoba, where the speed limit is 90 kph, “fines starting at 100 kph” and it lists how much the fine is for doing 100, how much for 110. So the Ontario gov basically sanctions doing 99 in the 90 zone, just dont do 100.

Meanwhile Ireland:

Ignoring largely empty stretches or highways where there’s practically no signs, have you seen how many signs are out there on heavily occupied highways?

We’re just coming out of Gulfport Mississippi, Highway 49 (don’t worry I’m riding passenger, not driving), and it’s pure information overload. When you’re surrounded by like 500 signs, McDonald’s, Circle K, RaceTrac, Shell, Chevron, this and that doctor’s office, etc, and you’re only looking for the BIG signs to see what exit to take, well its all too easy to miss the random speed limit sign that they don’t even post but once every 3 miles or so.

When surrounded by signage information overload, while you’re supposed to be keeping your eyes on the road, you simply cannot read every damn sign. You mostly keep your eyes on the road and follow whatever the pace of traffic is, only glancing up and around for the green signs with road names and highway/interstate directions.

The rule of thumb I’ve learned, is that no matter the posted speed limit, as long as you’re driving safely about the pace of traffic, and aren’t the idiot darting through 20mph faster than everyone else, then the cops generally aren’t gonna mess with you.

School zones are definitely an exception, you better be going 15mph along with everyone else, and of course following the directions of the traffic guards and bus stop signals when to stop.

TL;DR - Too much information, cannot read all signs and keep eyes on the road simultaneously.