I mean, "most private drivers" in Japan is a _tiny_ subset of people, no? Isn't a large part of that basically just rich people showing off?

Yes, like most other rich countries, cars are a status symbol. Kei car/truck basically says you are middle class or below. Regular size car/van is the flex, especially German cars.

All kinds of people who grew up in Tokyo are well aware that cars are required outside of a few big cities in Japan. Examples: (a) You have relatives that live in the countryside. (b) You take a family trip to the countryside for hiking or onsen/ryokan or skiing. (c) You watch NHK (public TV) about a small village.

I often get questions about train and bus coverage and they are surprised that you need a car in 2nd tier cities like Kobe, Nagoya or Matsumoto. They ‘know’ that having a car is convenient, they didn’t _understand_ that it was a necessity.

Don’t be that guy that thinks your experience of Japan is the only one.

Funniest thing my brother has sent me pictures of while living in Japan was a local guy in Nara who drove an imported H2 Hummer.

Cost is a major factor, but so is the convenience of driving (and parking) a car with a small foot print. Plenty of people who could afford a larger car opt to go with a kei car for that reason. My family has one large luxury car and one kei car, and for a lot of day-to-day stuff the kei car gets more use because it's more convenient to park or drive on narrow streets.