Consider also that if you tripled the number of doctors, supply/demand says doctors will make less money, making the prospect of suffering through 10-12 years of training (and N years of low-wage work) less attractive.
Again, medical care should be less lucrative for providers, and I agree that we should make it easier to become doctors. I just think that the long-term scalable solution for this problem has to involve more than just doctors. It only takes 4-6 years to become a nurse practitioner.
I had a friend that went to a prestigious European medical school for a 6-year program right out of high school. Is he any less qualified as a doctor than someone that spent twice as long to get to the same point?
Or compromise and make the students prove themselves for 2 years before being accepted into the med program. 8 years, they're done and "well rounded".
Currently, for every person accepted by medical school, there are approximately 2 people with almost identical grades/scores who are rejected. This suggests we could roughly triple the supply of doctors if we put effort into training more.