Remember, the world passed "peak baby" back in 2013. Population is leveling off in the developed world.
Moreover, who is supposed to have a monopoly on housing in San Francisco? Is there any single entity that owns even as much as 1% of all the housing in the city? And even if there was, wouldn't building more housing still fix it, because the more you build the more you dilute their monopoly?
Yes. 12 big landlords own a majority of SF bay area property.[1] The San Francisco Chronicle has an online map, but it's behind their paywall.
[1] https://www.fastcompany.com/90792419/12-mega-landlords-own-m...
Meanwhile the Chronicle says there are about 2.3 million total properties, I couldn't find them repeating the claim that those 12 landlords represent a majority but they did say that "this list of 12 includes some of the region’s major power players in residential real estate, housing tens of thousands of families". Which I wouldn't expect to be a majority of the >7 million people who live there.
An actual shortage is characterized by prices being prevented from rising. It is already understood that "shortage" is being used colloquially here.
The right generally takes as a given that the cause of the problem (if there is a problem at all) is that there is not enough housing and we just have to build more.
The left argues that in we in fact do have enough units that could be used for housing (or at least the situation is not as clear-cut), but that other factors prevent them to be available at affordable prices, like the effects of extreme income and wealth inequality on the market.
Personally, I think the "left-wing" explanation makes more sense - at least I've never understood where that sudden shortage of physical housing is supposed to have come from. We neither had a population explosion, nor a war or catastrophe that would have destroyed a lot of houses. So then why would there have been "enough" housing in the past but not anymore today?
It comes from construction dropping far below what was necessary to keep up with historical utilization in proportion to population after the Great Recession and, while it has recovered above the amount needed to keep up, it hasn't been far enough ahead for long enough to cover the accumulated post-GR deficit.
While this is a couple years old, it illustrates the issue: https://www.axios.com/2023/12/16/housing-market-why-homes-ex...
(And the national story undersrates the problem going on in lots of in-demand cities, which weren't keeping up with local need before the broader collapse of the GR.)
However that would still not explain the existing vacancies:
https://www.ourneighborhoodvoices.com/sfgate-there-are-more-...
https://www.axios.com/local/san-francisco/2025/06/27/office-...
OT, I found a look at the US population growth trends quite interesting, especially Figure 2 and the apparent massive explosion in immigration in the last years. Not sure what exactly is going on there.
https://www.census.gov/library/stories/2024/12/population-es...
By pure mathematics, there must be a shortage, and there indeed is.
There isn't any shortage in Ostrava where I am from, because the city lost 40 thousand people since the 1990s. But there is a shortage of well-paid jobs.
London by comparison is about 2.5%
Why is SFs figure so high. Why are people holding on to unproductive assets, paying to maintain them.
Dies SF have limits on rents that can be charged?
A world where most households are man + woman + 0..3 children is very different than one where most households are 1..2 people + cat/dog. The latter demands far more housing than the former, even when populations are otherwise equal.
A population of 10 million singles demand 4 times more "housing units" than a population of 10 million people in 4-person families.
This is what makes immigration-driven population growth so pernicious compared to childbirth-driven. The family structures you end up with are completely different.
Those housing units are not interchangeable. Families often want extra bedrooms, and units with extra bedrooms are frequently sorely lacking.
This is one thing that is very strikingly different in different markets. A lot of US metros have a fair amount of new housing but almost none with even two bedrooms per unit, let alone three. In a place like Taiwan, there are similarly absurd housing prices, but the new dense developments have four- and five-bedroom units.