> 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.

They don't have to sell their properties if they don't want things to change.

what's your alternative? (a) leave things they are and if people near cities get desperate enough they can move to the sticks even though they don't have jobs there (b) ?