One answer is that the market forces tend to funnel all increases in income to landowners as rent. I was not familiar with this theory until a few days ago, when someone here on HN linked to an online version (edited and abridged) of Henry George's Progress and Poverty [0]. I've been reading it since; its clarity is stunning: I feel as if a great veil has been lifted from my eyes. Whether I'll still feel that way in…
This is partially a result of Americans choosing to consume more housing than citizens of peer nations or, indeed, Americans historically. The size of the average owned American home doubled since 1950. You can save a substantial amount of money if you're willing to live like a 2015 Japanese salaryman or a 1950 American middle class family, but the modal American considers that standard of living "poverty" and is unwilling to accept it.
Another layer is that big houses gate access to good school districts, which is a very, very deep can of worms.