We've covered homelessness here.

The TL;DR is that it's not really a "homeless" problem. It's most often a mental health and/or drug problem, with the drugs often being the source of the mental illness.

The current approach in many cities is "Harm Reduction" coupled with "housing first" with the prevailing theories that if you just put the homeless person under shelter you can start getting them back on track.

The issue is that it doesn't work. As in, at all. Until you break the addict's cycle of addiction you're never going to free them from the grip of the drugs. They'll just keep using until they hit rock bottom. It should be mentioned that the Housing First units are almost always "Low barrier", meaning the addicts are free to do all the drugs they want.

Unfortunately both Harm Reduction and Housing First create perverse incentives among NGOs to keep these folks just alive enough to pay portions of their Social Security Disability (they all qualify) to the NGO in exchange for shelter in a tiny house or subsidized apartment. But since you've not removed the addiction, these tiny house/RV/public apartments become MAGNETS for open air drug markets and crimes that generate income for them to buy more drugs. And that's assuming the addict doesn't accidentally burn down their place.

Rhode Island's MAT program offers treatment while in jail (these guys commit plenty of crimes, picking them up for something is beyond easy) and has a high graduation rate.

Even San Francisco got sick of tourists stepping over needles and human poop on the sidewalk and passed legislation to address it. For one they got rid of Low Barrier Housing: Now ALL of San Fran's public housing is drug free and they will kick you out if they catch you using drugs. They've also kicked off a program they call RESET that looks like it's modeled after Rhode Island's.