At U.S. airports, the TSA typically requires adult passengers to take off their shoes before going through the metal detector (unless the sole is very flat), even if the passenger knows the shoes have no metal in them. (Several shoe makers started inserting fiberglass shanks after 9/11 to make it easer to go through security.) This isn’t the rule in Canada, though. These days, those going to America go through U.S. customs in a Canadian airport so as to integrate U.S. and Candian flights at U.S. airports. Customs comes before security, however, and yet the Canadian security rules still apply. So, if the shoe x-rays were really all that necessary — and I do not believe they are — this would create a security risk. More likely, it’s just another example or TSA irrationality.