States, including California have gotten rid of single family zoning and passed huge zoning reform bills and the outcome has generally been a minimal increase in what gets built.

Yes zoning reform is good, but it isn't going to create dense cities, dense cities require government spending & active planning, especially when a lack of regulations make It easy (and low risk) to simply sprawl. In the absence of green belt style regulation that forces European cities to densify, US only has dense cities where they were built before cars or where geography prevents sprawl, simply allowing developers to choose if they sprawl (low risk) or not isn't enough.