It's not just that. Houses are a consumer good instead of an investment, yes, but a large percentage of Japanese people live in apartments that are built to last and be renovated (because they ARE investments).

The difference is partly the attitude towards houses, but it also has to do with how difficult it is for foreign investors to speculate in the market, the ubiquity of public transit (which makes accessibility as a value-driving feature mostly moot), the way the building code precludes a "missing middle" (or "missing cheap place"), and other features of modern Japanese society that are alien to Americans (and Canadians, but weirdly not always to Britons).

The point is that there are lots of ways to chip away at the affordability issue. It's just that ALL of them necessarily attack RE investors' ability to exploit their property to the fullest extent possible.

One last anecdote: South Korea is similarly situated to Japan, but is also facing an extreme affordability crisis. So, there is the suggestion that NONE of the material aspects matter if the owner class is determined to wring every cent out of you. The changes disincentivize gouging, but in the end, you just have to have property owners willing to acknowledge housing as a an affordable necessity and not a profit center built on the backs of a captive audience...