You still get the problem where pickup trucks are a popular vehicle. It's not intentional (although perhaps from a lack of caring sometimes), but trash thrown in the back simply flies out when cruising down the highway.
I own a truck. It goes maybe 60mph downhill with a tailwind. If you leave anything lighter than a popcan back there it is flying out. A square box has terrible and unpredictable airflow. Truck owners who keep trash in their bed 100% know and accept they are littering. Do not give these asshats a pass.
