There is a a whitepaper that, in three parts, went into some detail on the situation in NYC, examining the causes and pulling apart the proposed solutions, for various of the complaints people have about the system.
> Critics of the medallion system urge that "competition" in the form of additional cabs be let loose to spur better service. The analysis below finds that the growth of taxicab leasing over the last 15 years has had a far more pernicious effect on service quality than has the medallion system.
http://www.schallerconsult.com/taxi/taxi1.htm "Factors of Production in a Regulated Industry: New York Taxi Drivers and the Price for Better Service"
http://www.schallerconsult.com/taxi/taxi2.htm "Villain or Bogeyman? New York's Taxi Medallion System"
http://www.schallerconsult.com/taxi/taxi3.htm "Fixing New York City Taxi Service"
> Critics of the medallion system urge that "competition" in the form of additional cabs be let loose to spur better service. The analysis below finds that the growth of taxicab leasing over the last 15 years has had a far more pernicious effect on service quality than has the medallion system.