[dragonwriter]

> I wonder if zoning rules aren't just another form of HOA that people voluntarily opt into by moving to specific cities.

It's the other way around; HOA's are largely an outgrowth of the real estate industry stepping in to solve the problem of how racial discrimination in housing could be made formalized and still publicly enforced through the courts when explicit racial discrimination by local governments in racial zoning was struck down by the Supreme Court in 1917; starting with racial restrictions, other busybody terms started getting adding to property covenants.

[nradov]

If you're going to have common use areas like clubhouses or private roads or even shared roofs on townhouse buildings then an HOA (or something equivalent) is a necessity to deal with maintenance, insurance, and usage rules enforcement.