Housing is the biggest expenditure for people in America and many parts of the world. Housing is cheap is Japan so people can get by on much less.
That's not what its downstream from, that's restating the same thing in financial terms. What it's actually downstream from is that Japan is a fully urbanized society. The reason why Americans cannot implement this is because houses are their little homesteads and castles, Fukuyama used the term "suburban villager" for this attitude (also prevalent in Greece and Eastern Europe etc.)
If you operate a rental in any area outside of the core of the major cities, you are in the business of charging a huge monthly premium over a property value that is rapidly depreciating to zero. This is fundamentally different than the US.