That part is the obvious part. I want to know how they got all the entrenched landowners to let new builds in their neighborhoods and drive down values. The NIMBYs are usually the problem.
https://calmatters.org/housing/2023/11/adu-san-diego/
Tons of San Diego houses have a ton of land thanks to the mid-20th century lawn fetish back when everyone was pretending that there was enough water so there are a lot of places where someone can turn some dead grass into as many as 5 ADUs.
You run into the same problem with free or heavily subsidized public transit. The trains were crowded in Germany when the government instated a temporary 9€ ticket for all public transit (buses, subway, tram, regional trains, etc) in all cities.
It is more complicated than that, for sure. I definitely pay for the roads in my city. And I pay for the mass transit in my city despite almost never using it.
It does not seem controversial that if you raise the cost for something, less people will make that choice. That does not mean that the underlying demand actually did not exist to begin with. If you made the cost zero, you would find the real demand.
This seems like the only real path - you cannot beat out these skeezy local homeowners and landlords at the corrupt local politics game. You need statewide politicians who have political ambitions to build off of solving these problems.