How can it be that the cost of *buying* a house in America has risen far more than the price of rent in the past few decades (when adjusting for inflation)?

A home’s value is the sum of its utility value as shelter, primarily the present value of future rents less maintenance costs, and its speculative value reflecting belief in future appreciation and opportunity value of the land. The second part can grow much faster than the first part.

That said, rent has only really become cheaper than owning since rates went up back in 2022. As recently as 2020-2021 your mortgage cost would have been cheaper than rent for the typical U.S. home.