I was in Los Angeles earlier in the week for the UCLA Anderson Forecast and an audience member brought up the lack of affordable housing in Southern California and what it means for the regional economy. One of my colleagues argued the problem was intractable because amenity-rich Southern California will always suffer from excess demand.
I then chimed-in with the comment that Donald Trump wants to keep people out by building a huge wall along the Mexican border. In in Southern California and other places the "enviro-liberals" are far more subtle. They have convinced government to impose strict zoning and environmental regulations to limit the supply of housing that have the same effect as Trump's would be wall. Simply put the regulations work to keep people out.
The only difference between Trump and the "enviro-liberals" is intent. To the liberals their intentions are good and Trump's are bad. No matter, the results are the same.