Basically everywhere in the USA (and I believe most of the world) has restrictions on minimum house size, maximum building coverage on the lot, height limits, s

Basically everywhere in the USA (and I believe most of the world) has restrictions on minimum house size, maximum building coverage on the lot, height limits, setbacks from property lines, room sizes, etc, etc, etc. Mobile home parks are one way to have lower cost housing, but far from the only one. They are much less common than in the past, as they are being regulated and bought out of existence.