And to close the circle, Prop 13 makes it impossible for towns in California to tax residents enough to pay for the required parks, schools etc. There is an obvious solution (repeal Prop 13, and bump local property taxes enough to cover the infrastructure the new residents will need) but it's politically infeasible.
Are developers expected to build those? Don't cities build roads, schools, parks, and police stations with the tax income from the people who live in the houses?
We've had this problem with developers as well - they want to build mega high-rise apartments with no parking whatsoever and force the city to deal with it, despite the city struggling to fill current transportation demand.
Sure, maybe. Offering to build them for the city is a great way to build goodwill for your project.
If you want to see the ridiculousness of building in the Bay Area, however, you only need to compare this project with another large project proposal somewhere else:
https://chicago.curbed.com/2018/5/11/17340660/the-78-related...
This is nearly the exact same size parcel as the mall in Cupertino. But they are proposing 10,000 housing units and 13 million square feet of development (5x as much). The article calls it "surprisingly low density". But the plans include a new transit station, new roads, many acres of public space, etc. What it will come down to, though, is that the city will say "if you build this, we'll build that". The elementary school that will serve this development is already under construction. So it's likely that the developer will pay for at least half of the train station - it would be significantly more expensive than a school because it is underground at that point.
Btw: The U.S. Department of Housing and Urban Development (HUD) defines "affordable" as housing that costs no more than 30 percent of a household's monthly income.
Building density housing is cheap compared to building the schools, parks, fire, police stations, and transportation to support the new density housing.