This is a great summary in the Atlantic:
[The United States] has the longest, most expensive medical-education system in the developed world, and among the lowest number of physicians per capita. ...
Starting in the late 20th century, medical groups asserted that America had an oversupply of physicians. In response, medical schools restricted class sizes. From 1980 to 2005, the U.S. added 60 million people, but the number of medical-school matriculants basically flatlined. Seventeen years later, we are still digging out from under that moratorium. The U.S. is one of the only developed countries to force aspiring doctors to earn a four-year bachelor’s degree and then go to medical school for another four years. (Most European countries have one continuous six-year program.)
