I can speculate on a few things that would reduce the rate of homelessness, economy, civil society, religion, but incarceration (where treatment is refused) seems like the only way to stop the cities from bleeding; open air drug use wouldnt be tolerated on private property (and where it is, fine, be my guest, I smoke, at home), it shouldnt be tolerated on public property either, dont be a menace.
Keep in mind that there are a lot of legal practices, or legally obtainable things, that still have a large black market. Its been historically proven again and again that people will gladly take risks or a loss in quality over affordability.
And there is nothing snarky about this. We've seen this exact scenario happen recently in certain areas of the US (e.g. Oregon) and Portugal where they eased off on criminalizing drugs use. You're talking about an economic weak group, where legality is less of an issue than cost. Them being 'homeless' is BY DEFINITION an indication of their poverty.
If you still want to double down on considering my post 'snarky', how can you also not say the same about 'https://news.ycombinator.com/reply?id=39580412&goto=item%3Fi...' in this very thread.
We need you (i.e. everyone commenting here) to follow HN's rules regardless of how badly other people's posts are. Moderation is inevitably inconsistent because we can't see everything; not even in the same thread.