Because we are in a different country. It costs them to prepare all the documentation, many U.S. suppliers won't do it, and Canadian freight rates are higher. Welcome to my world, I work in wholesale distribution. If you live near the border, obtain a U.S. postal box and pick it up there, many people do this.
The neighbor has a box in Point Roberts WA. any freight must come through Canada to reach it yet it is treated as a normal point of entry.:R