Different strokes.
As a Canadian, I can tell you it's extremely difficult to gain acceptance to a Canadian medical school. Last year in Ontario, roughly only 8-9% of applicants got accepted. Furthermore, unlike the US, there are few (I believe none, actually) private schools which take large amounts of OOP students, so really your only shot is within your own province. Californians will understand our pain. That, coupled with the few medical schools (17 total, 3 of which speak only french) led to an overall acceptance rate of about 26-27% for Canadian students. This is compared to a reported 44% rate for Americans. Personally, I was far more successful as an international student in US admissions than I was as a Canadian in Canadian admissions. That being said, not all Canadians can say the same, and I know of many Canadians accepted to Canadian schools who would likely have had zero chance at American schools (due to grade weighting in Canada). In addition, admissions are FAR more expensive for Americans than they are for Canadians. In Canada there are no secondaries, so your primary is basically it.
Regarding the prestige of Canadian universities, I had no such problems at my interviews. I graduated from the University of Toronto, and all of my interviewers had heard of it, and most were aware of some of the medical breakthroughs discovered there (insulin, stem cells, electron microscopy etc). I know publication rankings don't mean much, but U of T medicine is consistently ranked in the top 10 in the world, and I'm sure you'll find faculty in the US who are well aware of it, just as our faculty is well aware of the breakthroughs found at HMS, JHU, Mayo, CCLCM, etc.