I know a lot of my stops to pick up glass are alcohol related...usually in the form of Bud Light bottles from the weekend....I take exercise in a really rural area and drinking and driving is rampant here when you see the amount of bottles, cans, and empty beer boxes littered.
Who knows how many car tires I have saved for those who are littering in the first place. I still don't want garbage in the woods, but you would think it would be the better alternative than the actual road if they MUST throw refuse out the window. Steep fine here in the form of $1500 for littering if you get caught, but these are back roads so it's hard to actually see someone doing this at night.