re: How can we get people to understand what the left lane is for on interstates?

It takes about one YEAR and several thousand dollars to "EARN" a German license....it includes stringent classroom and road tests, in all driving conditions...i.e. snow,ice rain,city/autobahn training etc. Also, the vehicle you drive is thoroughly tested yearly for road worthiness and safety. The government invests HEAVILY in road-way design,maintenance and constant improvements....in short, one has to earn the right to drive over there...it's not your god given right to bring your idiocy to the public roadways !
Also, NO trucks allowed in left lanes....AT ALL...even used to ban truck traffic on Sundays {not sure if they still do that}...great idea though...we can all wait 2 more days to get the toaster,lawnmower and oven we need !