This, I believe, is due to a PR campaign by the health care industry in the US to discredit the Canadian system. Or better put, the Canadian system got trashed as part of the attempt to discredit universal health care in general.
It's true that Canadians love to complain about their health care. Health care could always be better, and there was a period of a few years when we had significant problems with wait times.
But our metrics are good. Canada beats the US on key indicators such as infant mortality and expected lifespan. Canadian women are not more likely to die of breast cancer than Americans, even when the wait time for a surgical procedure was a little longer. And while the Canadian system is much cheaper to run, the Canadian system is also more extravagant: Canadian hospitals tend to be cleaner, resulting in less superbugs and other side-effects of hospital stays; after-care is better; and so on.
The problems with the Clinton and Edwards plans are that (as far as I can see) they don't address two main areas.
(1) They don't address the issue of incredible inefficiency in the current US system, caused by too many profit-takers and too much red tape. Health care costs in the US aren't just a little higher than Canada: they're astronomically, mindboggingly higher. There is an impending crisis due to the retirement of baby boomers, but it is not due to inadequate funds in Social Security: it is how Medicare will be able to fund the health needs of retiring boomers at the current high cost of medical care.
(2) They don't address the issue of putting too many life-and-death decisions in the hands of people whose jobs are to cut costs. I have a cousin who was nearly denied a life-saving transplant because she was considered too ill to survive it (that was 10 years ago, and she's doing very well).
I can see that the US is never going to accept a fully socialized health care system. But a modified Canadian system - government-funded health care for all with the addition of private pay-as-you-go clinics - seems to be the ideal choice for the US. That is essentially what we have currently in Canada, because 95% of Canadians live within 100 miles of the border.