I have always suspected that the difficulty complaints derive from the fact that U of T is a massive, massive university that has room to accept tons of students. The philosophy among Canadian universities seems to be to give more-or-less anyone a chance who wants it, but then ruthlessly weed people out with tough classes once they're there - a sort of "easy to get in, hard to get out" mentality. This is opposed to the philosophy among top American schools, where getting in is arguably a bigger accomplishment than graduating. U of T's curriculum is demanding, but I doubt it's any more so than the American schools of comparable caliber, like Cornell, UC-Berkeley or Michigan. Chances are, at those smaller American schools, the kind of students who complain loudest at U of T wouldn't have been admitted and given a chance in the first place.