My wife and I went out this morning to pick up garbage off the highway as part of the Adopt-A-Highway program. Aside from the numerous Timmy Ho's coffee cups that littered the highway, you would be amazed at how many beer bottles, beer cans, and other assorted alcoholic bottles we picked up along the shoulder of the highway. And we only did ~2km stretch of the highway. There are no houses anywhere in sight, so the only place that these could come from would be passing cars.
Of course, maybe not everyone who drank them was driving at the time -- they could have been a passenger -- but even if 1/10th of them were consumed by the drivers, that's pretty scary stuff.