Only the really serious Scrabble players.

No, it’s practically impossible. In the current dictionary, there are 600,000 words. At most, an average talker will memorize 42,000 words. As to what conditions and status they’d have to be in to memorize that much, I wouldn’t know.

Yes we have to know them all before the age of 12.

Many words are just awkward Cronenberg creatures made up of parts of other words, so even if I haven’t heard a word before, it’s often not hard to deduce it’s meaning from context and components.

In university I learned a bunch of new words though, like inchoate, ameliorate, atavistic and suzerainty.

And reading old, old newspapers I learned of some great words that we just don’t use anymore, like ultimo. Ultimo means “of last month” and it was used a lot in old papers because news travelled so slowly 200 years ago that often the papers were reporting on something that happened weeks ago. The article would read like “Banker John Stoakes and wife were waylaid and murdered by bushrangers on 17th ultimo, perpetrators known to constables were tracked northeast into dense scrub.”

It’s a great word, I want to see it come back.

Here you go:

Not exactly what you are asking, but there have been several intentionally developed lists of words to help non-English speakers learn English, including BASIC English and Learning English. Most of these vocabulary lists are generally under 2,000 words, but over 1,000 words. Knowing these words, it is generally considered that you can start to have a discussion in English, either with a native speaker or with someone who also only knows these words.

I think that one thing which trips up a lot of alphabet based learners is that I can feel pretty close to knowing what a word sounds like by reading it even if I don’t know what the word means. I don’t know how I could do that in a logographic language.

Only the cromulent words.

No, we don’t know every single word.

But I think that isn’t really what most people are actually shocked about with regards to kanji…

The thing that is shocking about kanji is “how do you even pronounce words you don’t know? How do you even try to tell someone ‘i saw this word I didn’t know.’ when it’s a bespoke character for just that word?”

They don’t realize that most kanji are built by combining different characters. So if you know the base characters that a kanji is built from. you can make a reasonable guess at pronunciation (and sometimes meaning) even if you’ve never seen the word before.

In English, we learn from a young age to “sound it out”. At first glance, kanji makes no sense in that context. We can’t understand how you would “sound out” a new kanji

Outside of hearing brand new slang for the first time, t’s pretty rare for me to come across an English word I don’t already know. But if I were to read a dictionary cover-to-cover I would certainly find some. But those would be extremely rare and esoteric words, if I don’t know them it’s because I’ve never seen anyone use them.

People don’t learn their native language by memorizing a dictionary. They learn it from being immersed in it their whole lives. When hearing a unknown word for the first time, if you understood every other word in the sentence then nine times out of ten you’ll be able to infer the missing word from context.

Maybe sometimes you occasionally come across a rare word that’s not obvious from context, but the longer you’ve been using a language the rarer this is - you get better at picking things up from context and it gets rarer how often you even encounter unknown words to begin with.

There will always be words out there you’ve never heard, but if they’re rare enough for you to have never encountered them when using your native language your whole life, they might be rare enough for you to never encounter them in the future - unless you just read a dictionary to find them.

Average native English speakers know about 20.000 to 35.000 words

Do English speakers have to learn three different writing systems, one of which is entirely disconnected from word pronunciation?

For perspective, kids in Japan only learn 80 Kanji in their first year

Well…

All obstructions to the execution of the laws, all combinations and associations under whatever plausible character, with the real design to direct, control, counteract, or awe the regular deliberation and action of the constituted authorities, are destructive of this fundamental principle and of fatal tendency. They serve to organize faction, to give it an artificial and extraordinary force—to put in the place of the delegated will of the nation the will of a party; often a small but artful and enterprising minority of the community; and, according to the alternate triumphs of different parties, to make the public administration the mirror of the ill concerted and incongruous projects of faction, rather than the organ of consistent and wholesome plans digested by common councils and modified by mutual interests. However combinations or associations of the above description may now and then answer popular ends, they are likely, in the course of time and things, to become potent engines by which cunning, ambitious, and unprincipled men will be enabled to subvert the power of the people and to usurp for themselves the reins of government, destroying afterwards the very engines which have lifted them to unjust dominion.

—from George Washington’s Farewell Address, warning about political parties

It is bad when groups try to stop our laws. It is bad when they try to tell our leaders what to do. This harms our country’s main idea. These groups make one part of the people too strong. They want their own ideas, not what all the people want. Sometimes, a small group of clever people can do this. Then, the country’s rules change all the time. This happens when different groups win. The government then acts on their changing plans. It does not act on good plans made by everyone. These groups might seem good at first. But later, bad people can use them. These bad people want to take power from the people. They want to rule the country themselves. Then, they will get rid of the groups that helped them.

—the above text, run through this to target a first grade reading level.

That’s a pretty marked difference in vocabulary.

I’m always learning new words, and I had the nickname “human dictionary” in high school.

The short answer is, of course, ‘no’. For Japanese, I couldn’t even hand-write all the 常用漢字 without looking at some reference, but I also know Japanese words my native-speaker wife does not just because of medical, legal, and job-based jargon. She, who has a sports education, knows a bunch of other health, education, etc. jargon that I don’t.

Multiple countries have English as a first, co-official, or defacto language. I think it is difficult to paint an accurate picture that covers all of these, let alone if we include countries that have at as an official but minority language (and edge cases like international schools such as exist here in Japan).

You might be able to find per-country education guidelines online (though realize the US also does many things at the state level, so it may differ for every state at least there) which could give you an idea. You could also look at university entrance exams or similar tests to see what is being checked for at that level.

Is there a fast way to write Kanji, akin to cursive, joined up Latin handwriting?