Flying from Canada to non-US destinations is often MUCH cheaper because there's no TSA fees (which the US puts on the departing airport) for the return leg.
As someone from Buffalo it is (anecdotally) pretty common for Canadians to come here to fly to other parts of the US for cheaper, and for us to go to Toronto for cheaper international flights.
I just spent a few minutes on Google Flights looking at trips to various US holiday destinations like Miami, Las Vegas, Honolulu and Los Angeles. Every single destination was a lot cheaper (in some cases less than half price) when flying out Toronto compared to Buffalo. I wonder is a reflection on the collapse of demand for flights to the US.
Flying from Canada to non-US destinations is often MUCH cheaper because there's no TSA fees (which the US puts on the departing airport) for the return leg.