Taxis are highly regulated in most U.S. cities. There are a large number of reasons for this, most of which are suspect. You could argue that regulated taxi fares prevent ‘gouging’ of customers (although it still happens – and I can give you personal examples), and an argument can be made that screening and registration of drivers makes customers more safe.
The main reason that this job has been done by governments (at least until the Uber revolution has gotten around most restrictions) is that governments have taken this power for themselves and have used it to their advantage. A generous (or some would say naïve) view of this situation is that governments have benefited from the fees paid by taxi companies, and in turn have kept the system from taking advantage of people. A more cynical view is that this is an entirely corrupt system and a lot of city leaders have been on the take.
One way that taxis have been regulated is through the medallion system. A driver needs to have a medallion in order to drive and make a living. These licenses to operate used to cost small amounts: hundreds or possibly thousands of dollars. In recent years the cost of these medallions has become outrageous (a recent auction in Chicago for medallions started at $360,000, and they went for over $1 million in New York before Uber cut these prices in half).
It costs so much that the average guy who wants to run a taxi is kept out of the system, and big companies have come in that own the medallions and employ the drivers. This inhibits competition, stifles innovation, and in the long run does nothing for the people it is supposed to help. The ones getting rich off the system are the politicians and a few big companies.
So what does this have to do with MOC? The analogy should be clear. MOC is a pay-to-play system which is purely in place for the benefit of the regulatory agency (the American Board of Medical Specialties and its member associations). There is absolutely no proof that MOC benefits patients, and just as the justifications for regulating taxis, the reasons given are dubious.
Thankfully we have a remedy coming in medicine. States are passing laws which will prevent MOC from restricting the practice of medicine. The National Board of Physicians and Surgeons (NBPAS) is our Uber.