That's true, and is what I meant by my worry that cities will crack down to maintain the status quo.

Doing so is easily done as a consequence of Uber being centrally controlled, with full tracking on all its cars. A city can trivially know exactly to the minute how many cars are in operation via Uber at one time.

However, regulation of that sort isn't what Uber wants, they want a situation where supply is unbounded and people only compete/control demand.