To put it in tech terms, imagine if the FAANGs + 20 other big software companies had universities. Along comes the government and says that the only way for you to be a programmer is to work at one of these companies for 3-7 years. Oh yeah, and the FAANGs et.al. have an anti-trust exemption that allows them to collude on wages/benefits.

Pretty clear why that system gets abused. The result is that doctors have to pay 50k+ tuition for 4 years and then get paid (relatively) crap wages for 3-7. After that, they make bank because of how hard it is to become a doctor.

Existing doctors have been all to happy to pull the ladder up behind them. They continue to make it harder and harder to become a doctor by extending the training time. As a recent example, to work in a pediatric hospital now requires an addition two years time as a fellow. Of course, no current pediatrician is going to be required to do more training. Just anyone that wants to enter the field and compete now has to accept an additional two years of lower wages.

The linchpin holding this all together is the government license requirements for doctors. Take that away and it all crumbles.