What they have, instead of zoning, is a lot of restrictive covenants attached to the real estate deeds. So you can't just up and build a fertilizer factory in your back yard, because, even if the lack of zoning laws would allow it, your deed, and the neighborhood association groups that often enforce the restrictions, wouldn't allow it. Restrictive covenants also used to be popular to prevent you from selling to Jews, blacks, and other minorities, but those restrictions have been ruled unlawful. Nowadays they can be used to prevent you from painting your house garish colors, limit the types of fences you can put up, etc.