The exception to your line of thinking, however, is that it has already been done. About 10 years ago, Massachusetts made participation in Medicaid/Medicare a condition of licensure. LOTS of docs left the state at that time. I am uncertain whether it remains a condition of licensure or not but it HAS been done previously.
True, you may be able to make this a condition of licensure at the state level, but doesn’t guarantee an appointment. In the UK, at least a few years ago, physicians could set aside time for private paying patients and then overbook the other days with the public patients.
Unless medical licenses were federalized, some states would elect not to force physicians to accept government insured patients as a way to attract physicians.
Anyways, the old Soviet adage will always prevail “you pretend to pay and I’ll pretend to work” Physicians working under coercion will not perform very well. Just imagine how some of these office visits would go. Sorry, nothing I can do for you, the operation would be too dangerous and you could suffer harm or die. Here, take some morphine and I’ll send you for a second opinion. There is something open in 6 months. Or how about this: you were nasty to the staff and I will have to discharge you, here is your 30 day notice and a list of other providers. There will be almost no appetite among physicians for ANY risk, difficult patients, or difficult procedures.