The vast majority of the homeless you see on the streets in the US are there no because of money trouble, but because of mental health or drug issues (or both).
People with money issues can almost always lean on friends or family. It’s the people that no longer have any friends or family willing to put up with them that end up on the streets.
Then the question becomes why US has such a huge problem with mental health and drugs that most other countries don't have with this scale. Maybe it's easier to develop mental health and/or drug issues when there are no societal safety nets, like accessible healthcare, decent affordable housing, unemployment benefits, ...
I don't know why people seem to think the US has "no societal safety nets."
We have medicaid, unemployment benefits, how expensive our housing is completely depends on location just like other places (rural-ish areas are probably cheaper than almost all of Europe), etc.
We really should go with a harsh Chinese solution. If you do drugs in China, you hope your dad is Jackie Chan or you are going to have a really hard life. And being caught homeless in a big city gets you a free escorted bus ticket back to the poor rural area your hukou is in, where you couldnt make it either.
The more western solutions are compassionate containment like in Finland.
America cant make up its mind if it wants to be like China or Finland.
I live in Berlin and there's a ton of homeless people on the streets. As bad as most major US cities (SF is worse, or at least was - I haven't visited in a few years).
If they're spending money on, say, school lunches for poor kids and on substance abuse programs, they're not technically spending money on homeless people, but it's hard to see that the money that isn't being spent on the unhoused doesn't help people not become unhoused in the first place.
Closer familial ties + extremely harsh laws for drug sale and use. Asians realized how opium fucked China for a century and made sure none of that shit flies.