It is not illegal to own a car without a parking spot. Where did you even hear that?

In Japan you have to prove you have a parking space before you buy a car:

https://www.reinventingparking.org/2014/06/japans-proof-of-p...

https://jalopnik.com/why-the-japanese-will-never-buy-lots-of...

https://www.japantimes.co.jp/community/2017/06/04/how-tos/pa...

Kei cars (tiny city cars) don't require proof of parking so they are a popular segment of the Japanese car market.

Plenty of places, but maybe I misunderstood it. I thought it was illegal at least in the United States and Japan. I don’t know for sure, I don’t live in either country.

I suppose that may be the case in some strange places, but it's definitely not the norm.