Zoning is just one of many ways that people, through democratically elected governments, restrict private property rights in cities.
While Houston doesn't have formal zoning, a quick Google search (I've never been there) shows they do have extensive land-use regulation, including minimum lot size for single family homes (5000 sq feet) and requirements for parking for businesses.
So, if I wanted to place two single-family homes on my 9000 sq feet of land, or open a retail shop without providing parking, my private property rights would be infringed.
While Houston doesn't have formal zoning, a quick Google search (I've never been there) shows they do have extensive land-use regulation, including minimum lot size for single family homes (5000 sq feet) and requirements for parking for businesses.
So, if I wanted to place two single-family homes on my 9000 sq feet of land, or open a retail shop without providing parking, my private property rights would be infringed.