The same can be said in reverse for Japanese people on how they see the Western world: Do they assume the USA is like Hollywood or the UK being like British Television? They perhaps assume that all Americans live in a large home with a white picket fence depicting a nuclear family as if its 1950.
All they talk about US is California or New York since most movies and TV shows use either as their main setting. Is the US in real life similar to Hollywood (everyone having a nice car, big home & white picket fence)? That’s the kind of response from non-Japanese assuming Japan is like anime.
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.