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Because living is more expensive now than before. In medieval times, you had a 30m² wooden house on your farm that you probably built yourself, no heater, no car, no brand clothes, no washing machine, no electricity at all, no water pipes, etc.
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Because when you work on a farm for yourself, you keep 100% of your work. When you work for a company, it keeps most of your work for itself and gives you some compensation in return that depends on a combination of “how much do you need for living” and “how easily could you find another job”.
Not sure what you mean with the Anime part. Who thinks Japan is like Anime? All girls have huge boobs, everybody has colorful hair, people get reborn in Fantasy worlds, everybody is shouting and fighting with superpowers? Japan is NOTHING like Anime and I dont believe people think it is. But Japan is awesome and easily the best experience you can have as a tourist, no other country I have ever been to even comes close. Its like Japan is S tier and everything else is C and below. Living in Japan is different though, immense social pressure and horrible working conditions are apparently the price for a clean country with well-behaved people.
To answer what I think youre actually asking: Japan has a lot of very distinct culture, based on highly regarded principles like discipline and order. Thats easily romanticized. I think there are many ways people learn about parts of Japanese culture and lifestyle (mainly because of how distinct it is. There are hundreds of books and movies about Samurai, how many do you know about, i dont know, some part of Vietnams history?) and Anime is one of those.