So when you toss that bubble gum wrapper, you may very well be polluting public waters. Even if the water is unimpacted, littering is still a disgusting, lazy habit. We have all traveled on interstates and have observed how some portions of the highway appear to be more litter-polluted than others. That's a great idea even if some find it to be offensive in some manner. I suspect that inmates do not have to pick up too many soiled diapers before they decide that they never want to get into trouble again.
Visual pollution caused by littering is pollution, just as is water pollution and air pollution.
The problem is that we Americans want immediate gratification in every aspect of our lives. For some people, littering at 60 mph is instant gratification. You toss that cup out of your window while traveling so quickly that you don't even see the cup land. If you don't see it land, you do not have to feel badly because, in your mind, the litter evaporates rather than pollutes. Debris comes in all shapes and sizes, and can be lethal as well as unsightly.