One username here ends with 1998, which is presumably the year they were born, so a 21-year-old. The original iPhone was released in 2007, when that person was ten. These kids grew up with touchscreens, of course they think it's normal to have them everywhere.

Smartphones obviously aren't just a fashion, touchscreen all the things is a fashion.

IT fashions usually work that way - there is an actually useful killer application and suddenly the technologies used by the killer application must be applied to everything. Peer to peer (Napster), Ruby / "static typing sucks, testing is better" (Ruby on Rails), touchscreens (iPhone), JavaScript (one language for client and server), blockchain (bitcoin / getting rich through speculation), deep learning (great solution to SOME problems) - it's a fairly simple pattern.

Also, the car industry has looong product cycles, so what you see now is what was hot 5-ish years ago.

> Once something has been sold to nearly half the population of the planet for a decade or more, you can't sensibly call it a "fashion".

While I don't disagree with your main point, I have to say that this is wrong.

That's what fashion literally is. Everybody wears clothes and so clothes are sold to the entire population of the planet. Yet we don't dress like in the 60's anymore. Maybe some do, but you definitely can't find big masses of people dressing like in the early 1800's, for example.