They can sell to Canadians, however there are some stipulations from some manufacturers.
My car came from the US and I saved ~8k on it vs buying a new one from a dealer here. Hoever the stipulation was that if I wanted the factory warranty to transfer or an extended factory warranty the car has to have a certian amount of miles on it (can't recall the number) or be registered for 6months, whichever comes first. Luckily my car was almost exactly 6months old when it was registered in/imported into Canada.
