[twblalock]

Construction costs are a much bigger deal than NIMBYism or anything else anyone has mentioned so far.

We had easily affordable housing in California, including in Silicon Valley, until probably the 1990s. NIMBYism and property taxes (including Prop 13) have existed since the 1970s at least, zoning hasn't changed much since then, and geographical constraints are eternal. We also didn't have a Georgist land-value tax or any other nonsense; housing was affordable without all that stuff.

So why was housing cheaper then?

Well, consider the case of a friend of mine who recently built an ADU and was told it had to have solar panels because of a new state law. At least $25-30k is added to the cost of any residential construction just because of that one thing. That is only one of the many things that new buildings need that were not required in the past.

When you try to provide housing to other people the government makes you suffer for it.

We are regulating ourselves into this corner. Quite a lot of the building codes have nothing to do with safety or habitability.

[mixmastamyk]

Many moved out to the high desert by the mid 80s, because SoCal was already too expensive for working class folks.

Parking requirements are a big cost I've read.

[twblalock]

Parking requirements apply to multi-unit housing.

There are a ton of other silly requirements that get piled on top of each other and burden all new construction.

For example, if your house in California needs a new electrical panel to charge an electric car? $700+ permit for the panel, plus parts and labor. Adds up to several thousand.

There are definitely building codes that should exist -- earthquake safety, fire safety, etc. But quite a lot of them are just the state interfering in things it has no business dealing with, like the solar panel requirement that lets politicians feel better about themselves while making homes more expensive.