Japan culture is very different than US. There is inherent respect obtained from having a job, any job, and dedicated yourself to it no matter how small. Being without a job or worse, homeless, brings much shame to that person and their family. There is strong social pressure to maintain your career and pour many many hours into it.
There's strong social pressure to maintain your career and pour many hours into it in the US, too.
That doesn't have very much to do with whether there are enough places to live. If the places where the careers are have fewer available places to live than they have people, it doesn't matter how dedicated you are, you can still fall out the bottom of the market.
Correct me if I'm wrong, but it sounds like you're implying that homeless people in the US are homeless because they aren't ashamed enough of their situation to work harder and find a job, any job. That's... a gross misunderstanding of the problem, if so.
