[yonran]

> why is it that higher local wealth/economic productivity increases homelessness (especially if you control for public services to counteract the effect)?

May I suggest the book Progress and Poverty by Henry George https://www.gutenberg.org/ebooks/55308 that asks almost the same question. The answer is that private land ownership allows landowners to capture economic growth of prosperous places, so wages barely cover rent at the margin. This is particularly relevant to California which passed a disastrous constitutional amendment Proposition 13 (1978) which slashed property taxes from around 2% to 1% and declining, especially for older estates, which is pretty much the opposite of the ideal policy to deal with the problem of rising rents.