California being terrible is only a recent phenomenom. It used to be common to convert your sfh into an apartment complex. There are 5 story single lot brick apartments on my block that are still illegal to build on a neighboring lot today with SB9 and 10.

Even just straight up rolling back to zoning codes that existed in 1960 without much further change would do a lot for supply. Los Angeles in 2010 had a population of 4 million and was zoned for 4.3 million homes. Los Angeles in 1960 on the other hand had a population of 2.5 million and was actually zoned for 10 million homes.