...because of multiple government regulations that have choked off supply, namely:
* Rent Control
* Excessive environmental regulations
* Excessive land use regulations
* An institutional hostility to landlords (so bad that many landlords simply refuse to rent at all since renters could tie them up in court for years when they tried to sell the property).
* California's general hostility to development.
And now San Francisco has said they'll try to limit price increases by restricting supply. Looks like someone failed Economics 101.
Bonus: Did you know that the Rev. Jim Jones (yes, that one) once served on San Francisco's Housing Authority?