For some reason builders are skeptical in building or is it just that much red tape concerning building in the city .
It's the neighbors of all political stripes who all agree that "new people" scare "our people" so we want to keep them out:
1) New people tend to be richer, smarter, younger, and better paid, which is exactly why they want to buy a residence and exactly how they can afford it (and exactly how "we" were able to buy into a neighborhood x many years ago...and just like "we" forget what it is like to immigrate to America, we forget what it was like to be new in a neighborhood...and we treat the new people as badly as we were treated)
2) New people are new. We aren't friends with them and they aren't friends with us, so we are unfriendly towards them.
3) New people bid up prices that make it hard for "our kids" to stay, and "our seniors" to afford the taxes. So we resent them.
And then "we" mobilize to:
1) Pass zoning to keep things as they are
2) Testify against new developments at hearings
3) Act like people are bad, like only other people are "traffic" (not us) and spoiling "our" commute and taking "our" parking, instead of viewing people as productive, and serving them with stores and amenities can be exciting
Everybody is a "conservative" but also a "state control freak" when they want to keep their neighborhood exactly as it is, including people who vote for E.Warren and consider themselves environmentalists and community preservationists--who instead drive people to greenfield developments in Boston's exurbs or to cities like Houston which think nothing of greenfield development (but turn out to be "progressive" in their ability to provide affordable housing).
Anybody working to keep the city from growing and accommodating new
is part of the problem of housing affordability.