Two things that are different between SF in the 2000s and London in the 1930s (there are surely more, but here are two):
- land availability — SF is the tip of a peninsula. That means land access is limited and land value is high. London’s an inland city…there’s more land in all directions, and no other major metro areas nearby. People just keep moving further out for more affordable housing. When you move further out from SF, you run up against other similarly high-priced areas such as Marin and Silicon Valley. Oakland and East Bay are the cheapest option so that’s where everybody’s moving these days, which is driving rents and (pricey) redevelopment there…and the transit in a mess because you have to get across the Bay to SF and SV to get to the jobs, and there’s not enough capacity in any of the transit systems, and building more transit over the Bay/water, is expensive.
- building regulations. Regs get stricter over time…which drives up the price of building. Most regs are well intended: all new housing required to add parking, high efficiency lighting, minimum square footage per inhabitant, earthquake safety measures, etc. But when you add it all up, the costs mean that there’s no way to build affordable housing without major public subsidies. Small developers end up doing remodels and single-building rebuilds; any development of any size, ends up needing big pockets to buy old properties, pay fees, wait years for a project to be approved or rejected — which means only big developers can afford to do larger multi-family projects.