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!