https://www.npr.org/2019/07/01/737798440/oregon-legislature-votes-to-essentially-ban-single-family-zoning
The article says some of the zoning was as a means of racial and class segregation.
Back in the 50-60s-70s that may have been true.
But when I was looking to buy my first home, I looked into building. One community outlawed pre-fab homes after one person put one on the property he bought. Thing is, it is 2 floors, with the siding and roof on you cannot tell it was a pre-fab. It looked just like all the other homes in the community.
But it was the stigma of a pre-fab that sent the community into hysterics. It was all about protecting their property values! Not about racial or class segregation.