Uh, there are plenty of homeless in Tokyo, they do keep it tidier I guess. There are also homeless in Osaka and Nagoya. I assume other big cities have homeless, but I’ve only been to (and seen them) in these three cities.
That said it's nothing compared to the homeless situation in SF. My Japanese gf visited SF for 2 months, and she was seriously shocked by how horrible the homelessness situation was. She never imagined any developed country could have such awful conditions, and felt like she was in "the city of the walking dead."
So that's the reputation American cities are getting internationally. Something to really be ashamed about.
For point 3, it sounds like you’re saying that Japan has either a more abusive or cruel police force than the USA or a larger proportion of people locked up. I can only go by news stories and reputation, but I’d be really surprised if either of these were true.
It’s not “cruel” to enforce the law, nor does it require mass incarceration because people react to incentives. I suspect Japanese culture may be another important factor, however.
Japan has poverty and mental illness just like the states, but somehow they are more organized about “being homeless” and pooping in the street isn’t acceptable.
That being said, I’ve seen much worse in India and SE Asia, but developing countries will be like that.
There are about 13,000 homeless in all of Japan, a nation of about 130 million people. They’re almost all men whose careers bottomed out and they fell out of the system in their 40s/50s.
There is a woman who runs a program to move homeless men from the cities to rural areas that are short on labor. Her organization offers to relocate them and train them for agricultural work. Most of the homeless men she finds are willing to work but have fallen into a spiral of shame and are paralyzed by it.
Japan is a tough place if you have thin skin or are prone to self pity. You can basically be cut from the team if you aren’t a player. You’ll find hikikomori and others who can’t keep up lurking beneath the surface—-often they fail a test or disappoint someone and never recover. Usually, these people have a home, though, with family or someone who takes them in.