Echoing one of Matt's commenters who brings up something I've been meaning to mention for awhile. It is true that Houston has no zoning in the sense that you can stick commercial buildings next to housing (though the extensive use of land use covenants have established a kind of de facto zoning in many places), but Houston still has land use regulations which place serious restrictions on the type of structure you can put on a piece of land.
In other words, Houston doesn't tell you what you can do with a structure, but it still tells you what kind of structures you can build.
