The problem is that not only is there zero appetite to phase out housing-as-investment boosting policies like the mortgage interest deduction, imputed rent exemption, and cap gains exemption at the federal level, en vogue affordable housing strategies have focused on keeping interest rates low, providing 1st time home-buyer tax credits, and strengthening fair lending regulations. The U.S.(western nations with high ho…
The bigger issue to me is the constriction of supply. The suburban development pattern in many areas is simply unable to support the densities needed to manage regional issues well, causing traffic issues and forcing people to live very far from their places of work. I also have more unpopular opinions that there is too much "protected" land in areas like the bay area (specifically in the North Bay). Regardless of that, California needs to do better to fix the supply problem, because these housing policy failures are slowly beginning to affect more and more areas outside of just the bay area and SoCal, and the measures passed so far just don't cut it.
Also, prop 13 has essentially removed much of the "carrying costs" which penalize undeveloped land usage (prop 13 isn't the only thing here, IIRC there are also lots of state/federal tax deductions you can get from not using land, oddly enough). And the low property tax rates across the board really penalize young high earners since the low taxes are made up for with income/sales taxes.