alt Hacker NewsCivil Engineer/City Planner here. The bottleneck is legislative. NIMBY's are all over in US politics right now, local and larger. These folks put together legislation that makes it extremely hard to build without City/County/Township permission, unless the project benefits them in some way. So, most places will disincentivize new construction unless they get a grant for it, because they feel obligated to help their citizens by keeping taxes low and house values high. New construction does the opposite of these things.
This is exactly it. I built a house for 60k a few years ago in a HCOL area by finding a legal loophole to permitting/planning that bypassed civil engineers, code inspections, and almost all planning. The house next to me, quite similar and 50 years old, is selling for 5x that.
In the old days it was common to build your own house. And it usually allows a house for half or less the market price. But this is effectively illegal/impractical in most the US. Some simple changes to legislation would halve the average cost of a house overnight!