Thing is, they do it because they can. Because their disposable income is by far the biggest in the world, so their needs in everything else are more than satisified: they already overeat, have full two-car garages filled to the brim with "stuff", have enough of everything that people might want in "multiple" quantities. So what's left to spend money on, is either investments (this is their stock market is so insanely huge), or things one don't really need in more than single units - so they don't have many houses, but single BIG houses, same for cars. Which makes a picture of unaffordability, as natually if people's residual free incomes are so large, so much money is going to be pushed into these, they will indeed become very expensive as a portion of entire income, just because everything else (except healthcare) makes a so much smaller proportion. It's simply that it just means huge houses, a lot bigger than anywhere else except Australia (which is also Anglosphere!).
Want to make housing truly afforable? Make people poor, also make them die off to free up space. Japan does both with great "success".
Our parents did, maybe, but we're doing it because we have to.
Inner cities went from unlivable crime dens to highly gentrified in the span of about a few decades. The moment the crime went away, people moved back in. But most of the people who actually show up to town council meetings are the people who grew up seeing riots in LA and graffiti-covered NYC subway cars. So building any more of the now highly valuable high-density, mixed-use neighborhoods that inner cities have is a drawn out political fight with people who think making their neighborhood more valuable will ruin it.
And this situation also applied before the last major urban crime wave too. The low-density suburban neighborhoods that are also expensive now used to actually be affordable. You could build cheap housing on low-value land at the outskirts of town and sell it for a huge profit, to people who had extremely generous government loans[0]. This is what triggered the white flight[1] that started the inner city crime wave[2] that Americans now cite as why density is always bad.
Problem is, that's unsustainable, there's only so much land that can be near a valuable set of jobs. So now you have cities where both the high-density core and the suburbs are equally as unaffordable. The next rung on the latter would be to move to smaller cities, except then COVID happened, and suddenly the housing market was flooded with people moving out of San Francisco at the same time rich Chinese people were buying up houses to hide their money from the CCP, themselves in competition with hedge funds like BlackRock that want to buy up entire neighborhoods and rent them back to the people who lived there.
America's obsession with single-family home ownership is an unsustainable system, propped up by deliberate market distortions. We don't buy into it because we're so much richer than anyone else, we buy it because the system is built to make it the only option for most people.
[0] To be clear, nobody would loan you money for 30 years, on a fixed interest rate, and let you pay it back early otherwise. The amount of risk shouldered by the bank is insane, but for the fact that the US government pumps money into banks to make this kind of financing viable to offer.
[1] The peak of suburbanization happened before desegregation.
[2] Don't forget leaded gasoline! Once racial minorities were trapped in cities, we made their kids breathe shittons of lead fumes, creating fuel for the crime wave fire.
