I would say that there probably are some laws involved in some countries, but I think the overriding consideration of AVIS would be that Europeans are more "familiar" with the laws, customs, etc, of driving in europe than Americans are, the same would be true for American. I think it would be hard for AVIS to say since I live in Texas and I am renting in PA that I don't know the local laws (although it could be very true) I know when I have driven in other countries there has been a bit of a "learning curve" getting used to signage, diferent types of cars and different driving patterns.

I don't really think it is "discrimination" as much as experience. IE. Americans wreck more in Germany than Europeans do. Just my thinking.