Mvoight is correct, because by your definition, it would be discrimination to charge two different people who live in the US different prices for car rentals, airline tickets, and hotel rooms, all of which we know goes on, and all of which we know is not discriminatory. You are making quite a leap to say "purely on their country of residence." Ideally though, it would not be a requirement for the rez system to know where people live, but in reality, we know it is a necessity. Please also keep in mind that there are countries which are not members of the United Nations, and therefor their driver's licenses are not internationally recognized by treaty.