Inefficiencies of Niche Social Engineering

Poster prominently displayed near the restrooms at a central Washington highway rest stop. Questions that come to mind:

-Is a highway restroom really the best place to lecture people who presumably don't stop at highway restrooms?
-Why is the fine for this admittedly nasty practice equal to the lowest possible for "plain" littering?
-Is it really worth submitting every tourist and traveller to this fairly disgusting imagery--this being the last thing many of them will see before they return to the road?
-Is there a better way to address the issue (assuming that the problem is big enough to merit bureaucratic intervention in the first place)?