There's a lot more than just zoning, although that might be the single biggest factor. On top of that, the permiting process is insane, takes forever (I've gon

There's a lot more than just zoning, although that might be the single biggest factor. On top of that, the permiting process is insane, takes forever (I've gone through it), and costs a lot of money. Your neighbors get a very long time to file any complaints on your proposal (which they always do, because NIMBY). It is such a painful thing that I'd rather avoid doing any more construction. CA has a lot of rules that make construction very expensive, and SF even more so (only cast iron drain pipes, because ABS is somehow not good enough in this historic city). Earthquakes are real, but forcing everybody with 5 units (I believe) to retrofit (at the same time) cost millions of dollars per property - driving up the rent. And now solar power is mandatory for new construction, and solar is great, but it does add tens of thousands per unit.