You are absolutely correct. It does not make sense to purchase a US$15 board game with a US$24 shipping charge when using Global Shipping Program.
The program initiated almost three years ago was not intended for those low priced items. It is unfortunate American sellers use GSP when they should not. Shipping directly would be cheaper and more efficient for the buyers in most instances.
The program primarily was set up for American sellers not shipping outside their borders. With GSP they ship domestically (to Kentucky) and all extra costs are paid by the buyers.
All Canadian buyers can do is avoid these listings.