No, it's because American drivers don't look in their rear view mirrors and many don't care. They are oblivious many times and I have found the same thing when I'm on the highway in several of my cars. In Germany they know how to drive the autobahns and people get out of the way.....fast in most cases. The heads up displays on Corvetttes drop the 2 once your over 200 kph - so don't be confused by the numbers. Can you imagine American highway drivers reacting like this?
Having been in the Air Force there and gone back for vacations I think German autobahn drivers are the most courteous in the world.
http://www.youtube.com/watch?v=A1s6jzGtskI