I deal with these owners EVERY DAY who would rather sit on crappy buildings and land because why not, it costs them nothing. They've owned forever. Literally TODAY I had an offer rejected from a Seller that would have yielded 80 units of affordable housing in an area with $150k median income, delivering completion in 2028-2029.
Have a look at this graph: https://substackcdn.com/image/fetch/https%3A%2F%2Fsubstack-p...
You can see how even with prop 13, even with various RSO ordinances, even with red tape, even with building code requirements, the demand for development has always been enough to build to the limits of what has been allowed through zoning, ever since cities like LA were widely downzoned in response to redlining being made illegal in the early 1970s and succeeding zoning plans.
Zoning limits what and how much is permitted. Prop 13 changes the economics and greatly reduces churn and supply, both for redevelopment and migration.
Prop 13 takes the normal supply problems introduced by zoning and turbocharges them.
There's a lot of low-density sprawl in San Diego county which makes effective transit difficult, and because you have to drive everywhere, sentiment trends anti-bicycle. The previous CEO of SANDAG tried to push a mobility-centric vision but left because of intense pushback from folks who wanted more funding for roads and freeways, rather than transit and bike paths.
New families with some money spend too much income buying house.
Kids move out, parents get old and don't get out as much. Don't keep up the house, because they need to retire.
Sell house that's only attractive to lower income. Low income statistics take over the area.
Nearby businesses close from everything related to low income statistics.
Repeat with new families and newly built houses at edge of city, letting the interior rot.
Like a slime mold.
There was even a time when very large highrises were being constructed e.g. Wilshire Blvd's condo canyon. But that was also seen as a blight and quickly stopped in its tracks from expanding beyond the immediate arterial frontage. All hell would surely break loose if you allowed for student housing to be built on the eastern edge of UCLA instead of contained in the sliver of land between the school and veterans cemetery I guess. Unfortunately for the student body, the school is shoehorned in between two prestigious country clubs, and it is clear where priorities lay among local leadership.
Zoning in the 70s was more a response to (1) homeownership property value protection (2) nimbys being given the power to block projects like they still do today, especially in highly "progressive" cities. The more progressive, the harder to build (3) people claiming expansion was bad for the environment.
[0]: https://en.wikipedia.org/wiki/Guasti%2C_California
[1]: https://www.google.com/maps/place/Guasti,+Ontario,+CA+91761/
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