There's no big secret here. Dump restrictive zoning requirements, remove subjective approval processes, and make the permitting process a "shall approve" instead of "may approve", and you'll see a lot of new housing get built very quickly. All the slowdowns and immense extra expenses are self-inflicted by city residents who either don't care, don't want cheaper housing, or have been infected by the terminally brainle…
It's completely backwards to think that the reason why housing is expensive is because of those symptoms when the root cause is more than half the population wants mega high housing costs.