[eschaton]

It's mostly NIMBYism, but not just that. Proposition 13 has also played a role. It means that unless a house changes hands, property taxes cannot go up by more than 2% per year - which is of course generally speaking not only lower than property appreciation, but lower than inflation.

The proposition was originally put into place in 1978 in part to ensure seniors would not be priced out of their homes. But it applies to all property equally, and ensures that if you've owned a property for decades, you will be paying very low property tax rates, eliminating most of the incentive to sell. IIRC you can even pass down houses in families without your children getting reassessed.

The result of this is it fucks up the California housing market. People who in other states might choose to downsize to smaller units - or move within the state - just stay put where they are for long periods of time. On average, homeowners in the major coastal cities stay put around three years longer than they would have otherwise, which doesn't sound like a lot, but it means a lot of units which could be taken up by the local workforce are just kept off the market entirely.