I can tell you that my former primary care practitioner was a DNP - a doctor of nursing practice, with 2 subspecialties - pain management and geriatrics - and was equal or superior to every family practice doc I saw during the 20+ years I saw her.
When she became an NP, she had her Master's Degree in Nursing Practice, 8000 hours of medical nursing experience, and 2000 hours shadowing physicians in the clinic that hired her.
Why didn't she go to medical school? Because by the time she was "ready" she had a family, including a in a specialty residency husband, and could not manage the hours required for residency.
Until we figure out a way to train doctors humanely, and not use them as slave labor in our hospitals and Emergency Rooms, we will see declining enrollment. And until we compensate family practitioners equally to other specialties, we will see fewer docs. The year I retired as a technical project manager from the Feds, my NP and my husband's family practice doc both earned less that I did. I did not have anywhere near the education of either of them, and did not hold people's lives in my hands!
I have friends who really like their NPs and PAs. However, when one compares the full training, apples to apples, they do not have the same training and clinical hours requirements as an MD. I and others I know have been misdiagnosed by them or given incorrect information (even at Mayo). If one wants to practice like a doctor, one needs to acquire the credentials.
Of course, I have known doctors who were not up to par ...much depends on the passion one has for one's work.
I fully agree that one should not take advantage of residents and they should be paid. And doctors should be paid a salary (like Mayo Clinic, Cleveland Clinic do) and not this fee for service system that only promotes quick moving assembly line of patient visits.
Salaries are based on what the market allows, and by who controls the purse strings. CEO pay in the US is outrageous. Medicare could reimburse at a higher rate if one took the insurance company out of the loop and we had a single payer system. Just look at the financial documents of these insurance companies, the sales and marketing costs, administrative costs and CEO pay. And the provider has extra costs to process different insurance company policy rules. That is money that could go to increasing pay of doctors or giving us more benefits. That money does not go for healthcare!