There’s not an acre of open land between San Jose and SF that doesn’t have a building structure on it. Compare with most other US states where land is plentiful and they could use the economic boost of additional residents.
You are correct that all the easily buildable land is filled in, however it is mostly with suburb. San Jose is like 94% single family homes although that likely has decreased slightly since that statistic came out.
Rural areas where neighbors are miles apart tend not to be luxurious and in fact are very cheap. You can get 100s if acres of undeveloped land for next to nothing. It’s a very “city” idea that large quantities of land should be expensive. If it’s valuable to you then why not buy now while it’s cheap?
I believe GP was describing the [Land Value Tax](https://en.wikipedia.org/wiki/Land_value_tax). The idea being that a government invests in the infrastructure that improves the value of the land and because it's _public_ money funding those improvements, the property taxes should reflect the value provided.
No one would be forcing people to live a certain way, just forcing them to either pay for the privilege of living in an area that was granted public funding for improved infrastructure, or live somewhere else that received less public investment.
As a thought experiment, I find it easiest to understand the arguments for the Land Value Tax if you imagine a local government building a new subway line. Obviously, the existing homes around the new stops would have their property values increased. After all, many commute times were just cut in half! The local government is interested in more people living near those lines, more people == more tax revenue after all. If the local government had a Land Value Tax implemented, the infrastructure improvements they made to the area would automatically be included in the calculation for the taxes owed by the existing homeowners near the new subway stops. $1M/yr may sound insane, and it would be for a single-family home, but because of the new subway line, local developers are lining up to purchase the homes around that line in order to build new higher-density homes. The existing homeowners can either choose to pay the high tax and enjoy their short commute paid for by other taxpayers, or sell at a nice profit to developers. New higher-density homes get built, more taxpayers move in, the city can now build more infrastructure to improve the city!
But now where did the idea that the land that is privately owned being subsidized by the public? That’s an arbitrary add on that doesn’t reflect any reality in the US. So again, it’s changing the system to match another’s ideals on how people should live.
There's also a lot of open area in the yards and air 10-30ft above single-family homes. There are lot of property owners who'd be willing to demolish the SFH on their lot and build a lowrise multi-unit building with 2-6 units, and the only thing stopping them is that it is illegal to do this.
I have a question that is tangentially related to the OP, but not based on the irrationality of the housing market. What I want to know is: given the way things are today, how do you identify and locate neighbourhoods, towns, and cities where housing will appreciate in value the most? IOW, what is the data you need to make a good "buy low, sell high" decision?
Demand:
Interest rates(good luck predicting that)
Median income(predictable)
School districts (good schools attract people who care about that... as you can imagine that's a spiral one way or the other)
Supply:
Current inventory
Potential inventory
