This fact was implicit in a NYT piece that discussed the extent to which U.S. medical schools are expanding enrollments. The piece notes that the number of doctors in the United States is limited by the requirement that they complete a U.S. residency program. It doesn't give any indication that this protectionist restriction might be removed or weakened in the years ahead.
As a result of this protectionism, U.S. doctors earn on average more than twice as much as their counterparts in Germany, France, and other wealthy countries. This costs the country close to $100 billion a year in higher health care costs. Because of the political power of doctors, there is little public debate over this protectionism and news outlets like the NYT rarely even mention it.