That's what I've often thought while sitting on a local bus on the way to a mountain, (most often in non-western countries). Locals would buy a bottle of coke (vendors come sell it on the bus), and when it's empty, it's thrown out of the window, polluting the beautiful areas you're driving through.
As another example, I remember one bus driver who made a stop at a village, bought two plates with snack and coffee in a plastic cup. Once finished, threw it into the jungle next to the road. And he's probably doing that every day.
I've reacted in different pollite ways, but most often I was looked at by the passenger or driver as a crazy gringo, as if I was the bad guy on the bus. Most often it's even too late to react.
I was wondering how you react to such situations? Thanks