You're right...and it's disgusting to see people do that when it's so simple to slip it in a pocket...you've probably done the same thing as me which is to pick up stuff like that and carry it out yourself.

I use a very large 3XL good quality hunting vest with tons of pockets as an 'equipment vest' for hunting...(the same purpose as abackpack but with the load better distributed and many pockets within easy reach)...I keep alarge 2 gallon zip loc folded in the game pocket with the raingear to put found cans/bottlesinand pack them right out.