As the other commenter pointed out, the problem is primarily with the supply limit on taxis. Not limiting the supply of cabs artificially would result in more supply for whoever needs a ride, arguably lower the cost of a ride and help with more revenue for policing.
Making sure that taxis pick up in poor neighborhoods is an important, tough, and long standing problem. It would be disingenuous to argue that the "market" will fix it on it's own but then laws requiring cab drivers stop for all customers are routinely flouted, so it is not the case that regulation can fix this problem either.
The problem with supply limits is that once they are in place, everyone involved, other than the customers, has a vested interest in keeping the limits where they are for decades regardless of an increase in demand.
Increasing the number of taxis might decrease the number of cars on the street, especially in cities where public transport is not a viable option. Allowing more taxis certainly would decrease the demand for parking in already-congested central areas.
Definitely, although it's not clear that ride sharing will increase traffic for sure. Cabs and Ridesharing are essentially car multiplexing. Absent an on-demand ride, most people would drive into the city, and then park there.
Making sure that taxis pick up in poor neighborhoods is an important, tough, and long standing problem. It would be disingenuous to argue that the "market" will fix it on it's own but then laws requiring cab drivers stop for all customers are routinely flouted, so it is not the case that regulation can fix this problem either.
The problem with supply limits is that once they are in place, everyone involved, other than the customers, has a vested interest in keeping the limits where they are for decades regardless of an increase in demand.