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human
ELI5: Why are there so many different bread-type snacks in Japan?

For years, I've watched this Japanese youtube channel by the name of "shitemita", the guy does nothing but food unboxing videos, and I noticed that there's like a million different "bread with cream filling" snacks. I believe they're called "pan" (pronounced "ponn" like pond) in Japanese.

Literally, hundreds and hundreds of different ones, many different brands, some branded with cartoon/anime franchises, tons of different flavored fillings and different flavors of bread, etc.

Why are there so many of these? What has created such an incredible demand for "bread with cream filling" snacks? Do they just like them that much?
gpt
Well in general there is a bit culture of rapidly cycling fads in Japan, to an extent that would baffle most people in the US. We're largely familiar with their most unusually long-lived franchises, like Pokemon, but the average Japanese craze lives and dies in Japan (or some small part of it) in a matte of weeks, or months. In that time though, *huge* amounts of money can be made, and companies sometimes specialize in merchandising these fads. 

As for stuffed bread though... that's huge there, and not just cream-filled. In general though, a buns or breads are insanely popular in Japan... and most of Asia. In Japan though they have a particular style which eschews more traditional buns, and goes for actual bread. You find bread stuffed with yakisoba, or curry, or green tea custard. It's cheap to make, easy to ship, and relatively inexpensive. Students (and teachers) go for it a lot, but you may be getting a slightly distorted view from your source. 

Having said that, "fast" food in Japan tends to be much higher quality than in the US, and a much more viable option. Often fast food, ready-made meals in 7-11's, and bento sets in supermarkets are some of the only affordable sources of quick food for a lot of city dwellers. 

Finally... on average I'd say that the average Japanese person doesn't love sweets as much as the average Westerner. That's not to say that they don't like candy, but when it comes to desserts they're often more subtly sweet than cloying. An egg custard in bread, maybe with some sugary-cookie dough criss-crossed on the top is sweet, but not too sweet. 

So... external cultural factors: China started the whole "bun" thing, which includes the soft ones, but also more bready ones, some filled with egg custard. Internal cultural factors: variety-driven market, big market for fresh fast food. Palette. 

Having said that though, a far more universal portable fast food would be rice balls (onigiri).