You could hypothetically have on-the-job training for a surgeon, but it takes a lot longer and gets very expensive. That’s probably why they divide it up into pre-med, med school, internships, fellowships, etc. That and it means that companies don’t have to absorb all of the cost of training new surgeons. Maybe it’s not the ultimate solution to the problem since some doctors have difficulty paying off their loans. Unless you are in a highly paid specialty, you could be repaying your loans for many years.