I found this information to be usefull when I found out so I thought I would post it for everyone else.
I wanted to process US american express transactions through my merchant account but to do so you need to have an imprint of the card or open a seperate merchant acount with american express US. Why is it so difficult for Canadian merchants?!
Well for one US has different rules compared to what Canada has. Just like Visa/Mastercard has a different rules based on global jurisdiction, AMEX follows suit.
Not to mention US has it's fare share bankcard institution competition, which is not the case for Canada.