"To build housing in San Francisco, developers must first receive planning approval, known as entitlement, to ensure the city supports the type, size and design of housing proposed for a site. This part of the process took an average of 450 days over the last 18 months, according to recent data from the state."

Housing in the SF bay area is broken, largely due to the efforts of entrenched interests (developers and people who bought 50 years ago for an inflation-adjusted tiny fraction of current prices).