First - would this "free" service - be for anything.
Not for anything. Only for important things like if you would like to be more shapely or you have parts you don't think match your identity.
If you got a "boo-boo" on your finger, could you go to the doctor for a free band-aid?
I see you've been hanging out at a typical community hospital ER again. Yes, if you're on welfare or just don't pay.
Would the govt forbid some operations because they were too expensive and/or the patient too old/ terminial.
Yes. They already do that in many areas. We had people walk out of the cancer center every week because insurance and yes, Medicare, had rejected treatment plans. They also then have total control to squeeze doctors and hospitals to take less reimbursement. The docs respond by going into something else, offering silly services like botoxing women's faces. Hospitals cut and squeeze, use cheaper and dumber staff, limit services to profitable areas only.
Still, Salty, in our post modern world none of the people care about knowing if something will work. "Medicare for all" rolls off the tongue of a politician, especially if he has his sleeves rolled up, and tie loosened strategically, and also works the word "people" into the same speech. It's a winning issue and we're in trouble.