Because driving is the one thing the Europeans are by far more superior than us Americans. 98% (A low estimate) of American drivers just flat out suck and have no business being on the road.
And almost every state/region has it's unique incompetence. Here in New Jersey NOT ONE moron can grasp the simple concept that when going up a hill in order to maintain the same speed you have to press the gas pedal down a little harder, So on the slightest grade (NJ ain't exactly the Rockies) on 55 & 65 mph highways the idiots here will slow down into the 30s & 40s.
In Connecticut (BY far the worst drivers in the country) slightest curve in the road results in an immediate slam on the brakes and Lanes? What are they? (And no I don't mean Ct. drivers just change lanes without signaling they have a tendency wander out of their lane without realizing it)
In the Catskills it's "The speed limit is not 55 anymore?" and Pennsylvania it's "Slower traffic keep right - What's that?".
And I can go on & on.
To me, the main reason the Autobahn is safer than American highways is because YOU ARE ONLY ALLOWED TO USE THE PASSING LANE IF YOU ARE ACTUALLY PASSING!!!!
Why do so many American drivers think that THEY are supposed to sit in the passing lane and everyone else is supposed to drive on the right?