3 of the top 5 best hospitals in the world are located in America. 
Also, between 100,000 to 200,000 people come to America each year seeking medical attention. 
This proves that American doctors are some of the best trained in the world. Leading cancer institutions, neurosurgery techniques, and pain therapies have been developed in America. All of these discoveries were made possible due to the unique educational and training program in this country. Although undergrad can be long or not entirely correlated with medical school material, it functions as a filter to figure out all those who are genuinely interested in medicine. The academic and training rigor ensures that only the most qualified and dedicated students become doctors. Such a high standard of healthcare is possible due to the medical education and training required in America.