Single-payer already exists in the US

It’s called the VA:

A shortage of surgeons, nurses and auxiliary staff has created a backlog of 500 patients awaiting orthopedic surgery at the Veterans Affairs Medical Center in La Jolla, a surgeon who works at the hospital said Tuesday.

In some cases, those patients must wait as long as a year and a half for their surgeries, orthopedic surgeon Mark Murphy said, in response to questions from the North County Times. He added that 227 of the patients are waiting for joint-replacement surgery.