the problem is that there are financial reasons to deny health coverage to individuals. as long as insurance companies get to call the shots on who gets treated and how much their coverage entails, we will always have a fucked up health system in America. instituting a single payer system guarantees complete coverage for everyone, no matter their situation. it even covers people like the couple named in the article. if an American couple went on vacation in Canada and had the same situation, i highly doubt they would be stuck with a million dollar medical bill.
Most likely not even close to a million, but there would be a bill to your insurer. We don't pay for tourists, and most non-residents (foreign students yes, refugees yes, others mostly no). And your tourists would have gotten not exactly the same cares the Canadians got in the US (which in part would explain the much lower bill), and certainly not close to the comforts of a private US hospital, as in most provinces the costs of hospitalization, of ambulances etc. are often not covered (where I live, only elders don't pay for ambulances, for anyone else it can cost you around a 1000$). Not to defend your system which I find massively fucked up for seeing health care as a product and service purely subject to market laws (while the Tories who began the process introducing a public system - they were even more conservatives than the Republicans at the time - and other social measures saw them not as socialist compromises but as victories over the evil commies who thought such things were impossible in capitalist states) . But for all that liberal Americans tend to idealize our system too much. Sure, it has a lot of advantages - it's less expensive (relatively speaking - what we pay in taxes for it is under what Americans pay for their private insurances, or more usually their employers, who remove that amount from the salaries they offer) and it's much more humane and most Canadians would never go back to a system like yours, but it's still far from perfect.
Our insurer, the state, don't discriminate on who gets treated, but it certainly decides on who will go first and who will have to wait, most definitely on what the coverage entails (a lot of procedures and more expensive treatments aren't available), and on what treatments you will get. Meds are often on top, and for some, usually the most expensive, you have to pay full price, or even have to go to the US at your cost to get a treatment. We don't have the most high tech equipment found in private hospitals as we can't afford them, and when we have them they're hard to get access to, whether waiting, or having to travel far to get your test/treatment. If you want better or faster than that (waiting lists for some tests and procedures are terribly long - can take months or more to get a non urgent MRI a person with insurance would get the next day in the US), you need to go to private clinics and foot the entire bill, and we can't get a private insurance to cover that. Unlike Europeans, we also have nearby this huge neighbour with an highly attractive, more cutting edge and very rich private system always on the look out for the most promising talents coming out of our schools, of course most of all the very expensive specialists, and paying them kingly salaries. So we lose to the US each year some of our best talents, and experience shortages in many regions, and to limit that we have no choice but to pay too high salaries to our medical staff (especially in comparison to public systems that work well, like Scandinavia or even France). To make it worse, a huge part of the costs of those doctors's education was footed by the government, so we lose a lot of money when a student choses to go practice in the US, beside the fact that person took the place in public university of someone else who might have practiced here.. and we can't afford to train more than what we need. It's not always losses though. A friend of mine spent four years at Mayo before returning home (as planned from the start) and the cutting edge techniques he brought back have more than repaid for the temporary loss of his services.
A system like Canada's would never be viable in the US either unless a massive change in the way Americans think about health and about the state meddling in the private sphere in the name of the common good. Not sure some measures our provinces take to reduce the cost of public health care by reducing factors like obesity would sit very well with the American character.. limiting the size of sodas restaurants are allowed to serve or the amount of sugar they put in, forbidding many categories of aliments in schools (many public schools have strict "no junk" rules applying even to lunches) , forbidding fast food chains from opening restaurant within a perimeter near schools (usually: must far enough that students can't walk there for lunch), compulsory phys. ed until university, Etc. You would have to start relying much, much more on preventive medicine as well, which is not really ingrained in your culture, where limits on personal freedom are very hard to make acceptable.