This could happen if Uber manages to be cheaper by avoiding taxes or breaking speed limits; or in general does something that's good for the customers, but bad

This could happen if Uber manages to be cheaper by avoiding taxes or breaking speed limits; or in general does something that's good for the customers, but bad for society, and so is forbidden. I don't know that that's the case. In other places, it seems to manage to be net good for the customers, good for society, and mostly only bad for existing taxi companies. But "people are using Uber" is far from sufficient evidence to say that taxis are crap.