I wouldn't say that they're all doing it by trial and error. When this was done in my hometown it was explicitly done by a city council targeting a certain set

I wouldn't say that they're all doing it by trial and error. When this was done in my hometown it was explicitly done by a city council targeting a certain set of neighborhoods (that have since been gentrified). They wrote the law with such specific intent that they failed to see how it applied to anyone else.