Middle and upper class people are always desperately trying to figure out ways to keep people with anti-social tendencies out of their neighborhoods and away from their kids. As it stands in America there's no legal mechanism to banish annoying people, as was the historical way to handle this. Lower income is a very flawed but still useful proxy for criminal or otherwise annoying tendencies. So you get folks everywhere consistently trying to erect cost barriers to housing, because affordability excludes lower income residents. This is in reality one of the main reasons for the original suburban flight. The cost of car ownership necessary for suburban residency excluded social elements the new suburbanites were trying to evade.

If somehow there were a legal mechanism where people on a block could collectively say "No, these people aren't allowed to move in. Go away." Then housing would be way, way cheaper. Nobody would have nearly so strong an interest in driving up prices with artificial scarcity.