Section 8 is profitable, the number of apartments avaliable is severly low, it's low yield investing, so people don't invest in it.
If you don't want them shitting in the street, Maybe you need a city ordinance that all housing companies that rent or lease more than 5 properties must be section 8 available. Maybe you need a law that section 8 isn't to be the red tape nightmare that it VERY INTENTIONALLY is, as Republicans who can't eliminate these programs often settle for making them so absurdly difficult to use that they might as well be eliminated. Maybe it can be a simple program that's easy to use, then the profitability will seem more attractive, as it's already a profitable program according to rental investment companies.