Why is this so difficult?

Driving back from Madison to Chicago the other day reminded me how insane driving on American freeways can be. In particular, how hard is it to figure out that people driving slow should stay to the right and let people driving fast drive on the left? I hadn't realized how much more civilized it is to drive on the motorways in Switzerland until I got back to the States and had people doing 55 mph in the left lane. At one point near O'Hare the speeds were completely inversed--the fastest drivers were in the far right lane and the slowest drivers were in the far left lane. I've heard that passing on the right in Germany is considered a very serious offense, and I suspect the same is true in Switzerland also, whereas I probably passed more people on the right than I did on the left when I was in the States. Maybe it helps that there is less traffic (not to mention a higher speed limit) here, but drivers really do seem to take seriously that the left lane is for passing and that not everyone has a God-given right to drive in any lane at any speed at any time of their choosing.