NIMBYism and lack of housing development, whether by government or by corporations. In countries like Japan where housing is not an investment but a depreciating asset, people can buy homes. Because, well, they build enough.

Japan is a problematic example, considering their population has been in decline since 2010. That might have something to do with it

I mean in the major cities where had been still growing in the post war boom. Even looking back then, housing was still a depreciating asset, not an investment.