I live in a town on the Peninsula, inside San Mateo county. It's basically impossible to get new housing development, and the "affordable housing" requirements for any new development in this place have been 100% seniors-only (i.e. aged 55+) housing in the last few years.

The local government committee meetings on these matters is predominantly filled by two groups of people: those same seniors, and people who are effectively independently wealthy. It's NIMBY-ism all over the place here driven primarily by the wealthy and the old. I don't know if it's the same in other communities or towns in this area, but that's what it is here.