Bee 46
Yes, we all use cards differently. I'm not sure about Discover Card use in Canada, and actually don't see it used much in the US either. Discover and AE charge merchants a larger transaction fee than VISA or MC.
I also wonder about American Express Cards. We have traveled with friends that tried to use them without success, and AE Traveller's Checks seem to be a thing of the past? I also read that Costco will change their credit card from AE to VISA soon. It represented a large portion of AE's transactions. VISA is winning.