HR 676 !!! - Let's put Single Payer into the conversation:

[forthemiddle]

44. Are you sure it was the private insurance?

Obviously you have the first hand knowledge of the decision, but in my years of medical billing experience, the only time I have seen a Medicare secondary, or Medicare Advantage deny a claim was when It was a Medicare coverage denial.
In other words it was Medicare that said it was not medically necessary, not the insurance plan.

Medicare has ALOT it doesn't cover, contrary to what the public thinks. The reason most people don't realize it is because unless the doctor has the patient sign a waiver claiming responsibility before the service is performed, the doctor can't bill the patient.

Also, not pertinent in your Mothers case, but I wonder how many Medicare for All proponents realize how much it doesn't cover? Such as prenatal care. For the majority of Medicare population now, this obviously isn't an issue, but if Medicare expands to all, it will add billions of dollars to the budget each year, for this care only.