places where there is remaining land to build more single family homes don't actually have zoning regulations requiring developers to build high-density units. there is nothing stopping anyone from buying land and building there, except a lack of demand.

the place where there is leverage is in taking high-demand areas historically zoned for single-unit and opening them up to the market to build higher density housing.

> the place where there is leverage is in taking high-demand areas historically zoned for single-unit and opening them up to the market to build higher density housing.

And if the current residents don't want to open up, then what?

And they are not the only opportunity to increase density or satisfy demand, just the most politically convenient one for the party in power in almost every case.