But there are reasons.

Arguably, the main one is what's styled "zoning," in the stereotypically bland and euphemistic language of government-speak. It sounds innocuous. But it's evil. The word isn't too strong. It is not strong enough. The government says you may not use what for just this reason isn't your land; you may only use it within the allowed parameters. That makes it the government's land, which the government allows you to use. It's a distinction that matters, like the one between a "she" who is really a he and an actual she.

The parameters of allowable use are often uniform, meaning that in a given area, it is not allowed to (as an example) build a "tiny" house or park an RV on a piece of land you bought. Rather, you must build a single family home on the government's land you paid to use. A home that must also be built according to a roster of government requirements that in some states, such as CA, extend to requiring theat every new home be built with EV charging capability as well solar panels that can add tens of thousands of dollars to the cost of building the home.

Is it surprising that many people – especially young, first-time buyers – cannot afford a single family home in California? And not just there, either. This is a problem almost everywhere, because zoning restrictions are almost everywhere.

I italicize the word to make mention of areas that are not like everywhere else and so remain affordable, insofar as the land – because you're allowed a bit more latitude as far as how you may use the government's land. I live in such an area and moved to the area precisely to get away from the other kind of area where I used to live. Let's start with the latter to provide a point of comparison:

I grew up in and used to live in the Northern Virginia area, specifically Fairfax and then Loudoun counties. Both are among the most expensive places to live, assuming you don't live in a van down by the river. Last time I checked, a half-acre or so of land (which is considered a vast tract of land in Northern Virginia) typically sold for $50,000-$100,000 depending on the neighborhood. The main reason these plots are so pricey is because of what has to be built on them. It is why – in my old neighborhood in Sterling, which is a suburb of Loudoun County near Dulles airport, a small, nothing-special house typically costs upwards of $500,000 now. Nicer, newer houses cost hundreds of thousands dollars more and few of them are built on lots more than a half-acre or so.