There's a dust-up going on at the Volokh Conspiracy about Canadians traveling to the U.S. for medical care, and what this might indicate about the quality, cost and availability of health care. One commenter, an American physician with experience on both sides of our border, has this personal observation:
I was working at a hospital in Kingston, Ontario when a US citizen truck driver came in, after a rather bad traffic accident. He didn’t get health care at all (we were stopped by admin) until he signed a waiver of his rights, and showed he had insurance that the hospital could bill.
Conversely, in the US a federal law (EMTALA) prevents us from asking about a patient's ability to pay, and mandates that he be given emergency, stabilizing treatment (which often means full treatment).