Or just simple misaligned incentives. At the time communities are formed and lots are subdivided, they're planned out based on the prevailing population densit

Or just simple misaligned incentives. At the time communities are formed and lots are subdivided, they're planned out based on the prevailing population densities and consumer desires of the time. People move in because they like how the community feels, and then are disincentivized toward changing it because any change would take it away from the local optimum that they bought into. The people who would benefit are those who don't currently live in the community. Property owners get a vote; prospective property owners do not get a vote; ergo nearly all communities are biased towards the needs of existing property owners over newcomers. Talking to boomers, I don't get the sense that either racism or property values are the motivating force behind zoning restrictions. Rather, they want to preserve privacy, natural beauty, traffic, neighborliness, and the general aesthetic that they bought into. Racial discrimination, high housing values, and homelessness are consequences that fall out of that, but most people voting for these policies are not thinking about those. It's "fuck you I got mine", but out of apathy rather than malice.