Assuming that the infrastructure of sewers, water, and electricity exist. Unless we do deport the illegals, they do not. Just the cost of upgrading those utilities for an ADU can exceed the cost of the structure because of said regulatory requirements. How Hilton proposes to move county bureaucracies Statewide on that one I cannot envision.
ADU’s are the answer if towns can get behind it. The ideal would be your standard 7500 sq. ft. lot with and an alley in the back where utilities are connected. Container housing would work-start out with a 320 sq. ft. shell and grow from there. People are living alone more and don’t need much space. A small stick house went from $100k to build to 300 over 6 years in my town.