What's the argument that taxis increase congestion? It seems it should do the opposite. First, people are more likely to share taxis than carpool. Second, taxis drastically reduce parking congestion since dozens of people can utilize the same vehicle in a day.
The problem is that there are literally too many cabs on the road. Cabs rarely, if ever park, and are constantly driving. Parking, and this may seem counter-intuitive, reduces road congestion. If you have many vehicles constantly being driven, it increases congestion.
