That's when they resort to the bribery which they call rent control. Instead of building more housing, they give existing tenants (who can vote in the jurisdiction) lower rents than prospective tenants (who can't). Which moves enough tenants to the other side of the ballot to keep the construction restrictions in place, and further reduces the incentive for new construction, raising long-term rents even more.
Prohibiting rent control at the state level would be a great move because economists broadly agree that it's a terrible idea and then you get all the previously paid off tenants whose rent would increase clamoring for other measures to get housing costs down and increase the incentive for new construction. (Many other states sensibly already prohibit it at the state level.)
In California rent control is established by a referendum so it requires either another referendum to repeal or a some large majority in the legislature (which is unlikely to pass since the legislators understand that it's likely to be their last legislation). You cannot take away free/cheap stuff from people in a democracy, nobody is going to vote for that.
Rent control is a huge pain the ass because it's simultaneously supported by fatcats who know exactly what it does (i.e. raise overall housing costs) and naive idealists who think they're sticking it to the fatcats.
Prohibiting rent control at the state level would be a great move because economists broadly agree that it's a terrible idea and then you get all the previously paid off tenants whose rent would increase clamoring for other measures to get housing costs down and increase the incentive for new construction. (Many other states sensibly already prohibit it at the state level.)