Geez these UofT threads get crazy.
Look, I can offer a bit of insight as I did my BSc at St. George and also took science courses at UTSC, Waterloo, Guelph and York for various reasons. None of the courses (except for orgo at UTSC) approached any of the St. George campus courses (well, maybe just BIO150) in terms of difficulty. This isn't just related to the sometimes ridiculous tests downtown; it's also related to the volume and depth of the material. Saying the class averages at York or anywhere else are also 65% (which is often true) is meaningless without a discussion of the calibre of students and the course outlines/expectations.
Think about it: the number of individual life sci programs offered downtown is unmatched at any institution in North America. Don't believe me,
look here and try and find another with more. Remember to look within each broad program category e.g. Biology, as well as there are "subprograms" as well. Clearly a student in an Immunology specialist program will be expected to know more immunology and at a greater depth than one in a micro+immuno program (as is found nearly everywhere else) or a straight bio program. The same goes for the molecular genetics program, or nutrition, or pathology, or physiology (which has a theoretical stream and others). The list goes on. And the grading policy for the Faculty of Arts and Science is true.
Is UofT the hardest place to do a life sci undergrad in Canada. It likely is, but nobody's completed degrees at every school so definitive proof won't be forthcoming. Keep in mind that UofT had the 2nd or 3rd highest entering avg in Canada according to Maclean's while being by far the largest school (more spots) and with large humanities/social sci/suburban campuses that have lower admission standards. I'm not going to get into class sizes or the quality of teaching as that isn't the topic here.
Now the big question is whether it will help you get into meds. In Canada, the general answer is no, though UofT does consider the academic rigor of the applicant's program, whatever that means. It won't help you in the US either if your GPA isn't competitive to begin with. Nobody will take a UofT grad with 3.2 over someone else from a reputable school that has a 3.7, everything else being equal. UofT meds grads are highly regarded in the US, but that's at a different stage of the career ladder.
As for the Ontario vs Alberta thing, do some research. Both provinces are the only have provinces in the country and thus rather than taking from the other, they are the only ones that contribute to the equalization payments.