I used to do this around my row home. The kids next door were one the worst about throwing stuff on the ground. I was out there doing my trash collecting one day and the youngest kid asks if she can use my trash grabber. She enjoyed picking up the trash for a bit and then went inside her house. Thought maybe that would make an impression.

Next day saw her throwing her trash on the sidewalk...

I was at a traffic light on Fairmount years ago and dude in front of me opened his car door and put his empty Popeyes box on the ground. Shut his door and drive off.