California, especially the bay Area, is notorious for being anti-development. The landed class will furiously fight any attempt to build dense housing, to keep property prices high. Rent control exacerbates this as most residents have no incentive to solve the housing shortage since they aren't affected by price increases.
Washington, by contrast, prohibits rent control statewide. It's no coincidence I'm seeing far more construction in Seattle and it's suburbs than I did SF.