There would be high demand for buying land to build new homes on. Or buying land with old low-rise buildings, and replacing the buildings with higher and&#x2F;or more efficient design, to provide more homes on the same piece of land.<p>But even if the owner would like to sell the land, and buyer would like to pay a lot of money, this is usually not allowed, for political reasons.<p>If let to operate more freely, free market economy would be efficient in increasing the density of homes in high-demand areas. This is very much not happening in San Francisco.<p>If people are willing to pay Manhattan-prices (and even more), the free market response would be to build at Manhattan-density.