Where are they built in relation to necessary services, and what other services are available?

Is there on site support for drugs and mental health issues?

Is anybody’s stuff going to be safe there? Or are they dumped out of sight and mind?

You have to ‘invest’ in preventing the causes of homelessness in the first place, which has proved impossible under capitalism. I doubt corrupt dictatorships of the proletariat such as the Soviet Union did any better.