We aren't offering treatment for free or even making sure there is enough treatment available. We are more likely to put them in jail for a small crime instead. Same with drug addiction: We tend not to offer free, medical based care and instead refer folks to AA or NA. I understand that some folks are helped by these organizations, but many are not.
We don't make sure folks have homes. Sometimes, simple solutions like driving a person to their home over and over is enough of a solution. If someone really wants to life outdoors, we could make room for such things while making sure things look nice and are secure.
We could have an actual safety net too keep folks from homelessness in the first place.
We can invest more in group homes as well, since some folks need help with everyday tasks. Some folks need this long term and some are just short term.
Have enough shelters for the folks that slip through the cracks. Make sure these shelters are safe for disabled folks, children, and everyone in between.
I know all this stuff costs money, and I'm more than willing to pay more in taxes so that folks are being fed and housed and have medical care and things like that. Honestly, we are paying for this stuff in one way or another anyway through our jail system, public services, and so on, so I'm not convinced it would have been that much mroe than it was when I was living in the US anyway.