The zoning didn't come from nowhere. It's no secret the Federal, State, and Local governments encourage home ownership through policies, programs, and specific tax benefits. It then logically follows that single family homes are the golden standard in America. Which then logically follows that single family homes are built a lot (which do require much space). It then logically follows that the people who move into single family homes want single family home neighbors, not dense apartment or housing structures, as evidenced by the zoning laws which are typically passed at city councils with vocal citizen participation. Read into other reasons or causes that surround those facts (NIMBYism, racism, whatever-ism), but these are the basics. I also would expect any group of people to act similar fashion, regardless of demographics or other superficial characteristics. People are protective of their neighborhoods.

So that is to say, the situation we have arrived at, however unfortunate, is entirely unsurprising, and not that hard to figure out why it is so.