https://www.cnbc.com/2018/08/10/whats-the-right-number-of-taxis-or-uber-or-lyft-cars-in-a-city.html

When Uber and Lyft first entered the market, offering a ride-hailing service that would come to include tens of thousands of amateur drivers, most major American cities had been tightly controlling the competition. New York City allowed exactly 13,637 licenses for taxicabs. Chicago permitted 6,904, Boston 1,825 and Philadelphia 1,600.

These numbers weren't entirely arbitrary. Cities had spent decades trying to set numbers that would keep drivers and passengers satisfied and streets safe. But the exercise was always a fraught one. And New York City now faces an even more complex version of it, after the passage of legislation this week that will temporarily cap services like Uber and Lyft.