Easily the biggest cause here is the insane cost of living California has, which is largely a 'self-own': regulations make it hard to build out <i>or</i> up, and with those kinds of constraints on supply, the impact of high demand is predictable.<p>This isn't a result of the normal partisan political issues, but it's true that there's still a political source: more 'red' metros and states usually at least permit building outwards with suburban sprawl, even if they're hostile to density. Most of coastal California is hostile to both. Even more sympathetic cases like building 100% affordable housing for seniors get pushback from the NIMBY crowd: <a href="https://sf.curbed.com/2016/10/6/13189882/1296-shotwell-affordable-housing-opposition" rel="nofollow">https://sf.curbed.com/2016/10/6/13189882/1296-shotwell-affor...</a><p>Broken down, there's a few different problems that I've read about or seen:<p>1. Most residential land still has fairly strict limits on density. Even in the bay area, a majority of residential land appears to be reserved exclusively for single family homes. In areas where this isn't quite as much the case, like SF, there are still limits that greatly constrain supply in what is ostensibly a major city.<p>2. The process of development involves a huge amount of time, money and hurdles. These come in both official ones, like CEQA, which has kind of morphed away from its original intentions, and unofficial ones, like needing to please the local neighbors even if your new building completely fits within existing regulations and codes.<p>The last bit is particularly problematic: you essentially have the rules that exist on paper, the ones that were democratically discussed and voted and agreed upon in some form. And then you have <i>another</i> set of rules, the ones that exist solely in the minds of the local residents, that nobody ever voted on or transparently discussed, but are nonetheless hurdles that you must pass. And in practice, the power of these rules tends to correlate with how wealthy and entrenched those interests are.<p>Like, take the example I linked to. If "there's not enough parking" is a real problem, then why isn't it in zoning regulations as is? Why does it come up as a surprise, "Actually jk, you need to do these other things that the law says nothing about"?<p>What causes these issues is that SF agrees in the large that, say, minimum parking requirements are damaging to the urban fabric and bad for the environment, so they or their representatives reduce or get rid of them when it comes time to vote. <i>BUT</i>, then when it comes time to actually have such a development, local NIMBY's cry out that their parking will be impacted, and the process lets them stall or outright block the new building, actual regulations be damned.