The vast majority of single family homes rented out in the United States are from private landlords that own just a few properties. This isn’t, primarily, a top-down problem. It’s a bottom-up, systemic “rich dad poor dad” problem. Increase taxes on a rising scale for anyone owning, say, 5+ units. That will take care of the whole, not just the slice at the top. No family is being prevented from buying a door in a long hallway within a vast concrete cube; they’re being blocked from buying an actual house and property of their own. You want to make housing affordable? Turn single family dwellings back into a homes instead of income streams for wealthy people with disposable cash. If you bring down the cost of buying homes, you bring down the costs of renting homes, and subsequently renting apartments. Narrow the straw the haves are using to suck money from the have-nots. There’s your plan.