Many if not most Americans when they travel are shocked to find out the US dollar does not reign supreme. They expect everybody to be able to express prices in the only currency they understand or wish to understand namely US dollars. When they pay cash, it is too much for many of them to take a few minutes to learn the coins and be able to count out small amounts, can't get it through their heads that in most countries today, the smallest paper money is 5 units of whatever. And for the most part never think clerks are trying to rip them off (in fairness to the clerks, often students, they are just doing what they're told). And when a clerk tells them they can pay in US dollars so they'll know exactly how much something costs, they are amazed at the courtesy being extended on a credit card payment. Simply the way it is.