The same is not true for just existing --- being a legal resident of the United States. Just "being here" creates negligible risk of calamitous damage to other persons and their property.
On physician supply and climate of care: Of course there are many factors which influence the supply of doctors: number of openings available in med school, the burdens of student debt, etc. But a big one is the climate of care. With the disappearance of freestanding doctors' offices, small practices and even small hospitals --- due to much higher overheads, complex record-keeping and omnipresent minute regulation --- the care environment becomes depersonalized, even "industrialized." Couple that with stagnant or dropping levels of compensation, and you see lots of doctors leaving medicine (Link) and patients suffering from big declines in personal care.
Literally hundreds of thousands of examples of this in the U.K.
NHS: shabby, unsustainable, our future.
This leftist stray alley cat ksen sneaked in here and now wants to be fed. If fed, it will shortly demand the right to keep on being fed.