That's the line they want you to believe. Explain why cars (foreign and domestic) are charged a fee called 'freight' in Canada and not in the USA (at least to my knowledge).
The cars are shipped virtually no further (>80% of the Cdn population lives within 200km of the border).
Open your eyes. They charge the difference because they can. That's why we have 'Canadian price adjustments' and 'cash incentive', its because in general we don't stand up as consumers and call them on this bullsh!t.
Its possible to save over $20k on a car just by locating a dealer in the US and paying a $200 import fee and some taxes (which you would have to pay anyways). And more people have been doing that lately.
Companies have caught on that consumers are demanding fairness and have begun to omit the US price on greeting cards for example. Its a big circle where the Canadian consumer gets taken.