I don’t really follow what you’re saying about hospitals. If the hospital’s policy is to accept Medicare, then fine, all the hospitalists and other medical employees do by default. Individual physicians with hospital privileges may or may not, but if they don’t, they will only admit non-Medicare patients anyway and so it’s not an issue while they’re making rounds or doing procedures in the hospital. I think it is quite rare for any hospital to not accept Medicare, unless it is some sort of a specialized, private hospital (such as drug treatment, maybe).
Not too many doctors actually work for a hospital, these days, outside of interns and residents. Most private practice doctors have “privileges” at various hospitals that they have signed up to perform medical procedures or see their patients.
The hospital can have a policy that they will see anyone, including Godzilla but, if there is no doctor (again, excluding an intern or resident) who will treat the patient, the hospital’s policy is pretty useless. At this point, the hospital “policy” could end up being to make certain that a patient is stabilized and transfer them to a teaching hospital (typically one that is state or locally suported through a tax) that cannot refuse the patient.
Ultimately, it is not the hospital’s policy, but the doctors with staff privileges that determine who will or won’t be treated. And, as more doctors decline Medicare patients, more hospitals will have no choice but to transfer the patient to a teaching hospital. As it is, most teaching hospitals are overcrowded with indigent people who can’t afford to pay to be seen, much less treated, for a given illness or medical condition. So, a transfer patient who isn’t bleeding copious amounts of blood or whose heart is still pumping will end up on a gurney waiting their turn to be seen by an intern or resident.