Market prices of homes in places like Freemont tend to run from the high 6 figures through the low 7. Knock off $150k and we have maybe a 20% price reduction (probably closer to 15%). Nice to have but hard to figure out how that represents the largest portion of anything.

Land homes sit on costs more than $150k, maybe north of twice as much in Freemont-like areas (unless the lot is weird, inaccessible, or otherwise has issues that make it difficult to build on).

I'm not sure how one is going to get total materials and labor to come in less than $150k for most single family homes in CA. Maybe with small square footage and a good deal of luck with labor and materials? You tell me how to build for less than $120/sqft and I'm sure I'm not the only one who's all ears.

Seems to me to get regulatory expense to be the single largest item for building a home, we'd have ignore land, then play the game of lumping together all such expenses while splitting out building and labor, and even then I'm still not sure how it actually adds up.

The land cost scales down with density. The unit permitting cost is fixed regardless of size.