[goobatrooba]

Just to stress that the world is larger than the US. Zoning exists pretty much everywhere and the reasons for its introduction were diverse and mostly about quality yof life, citizen health, or city esthetics (keeping polluting businesses out).I have no view on whether what you're saying is true for the US, it is however definitely false for most other places.

[Schiendelman]

In the vast majority of the world, you can trace it to class and race. Feel free to give me an example location and I'll find you its history!