Taxis are state-sanctioned cartels in many cities. The number of "licenses" (medallions) is capped to inflate the revenues of existing businesses. In San Francisco (where Uber's legal problems are), the quota is ~1,400, and there's a waiting list more than 10 years long to get a "license".
This cartel appears to be the product of a joint effort between the taxi corporations and the drivers union. I don't hear the cab firms arguing for greater competition or an increase in the number of taxis either.
Or is something preventing them form doing that, because licensing is inherently a way to protect old cartels from new cheaper/better upstarts?