A walk down the road where I live is a chance to enjoy the greening of the earth and hear the birds singing and all that spring can bring....including all the roadside trash like fast food bags, plastic and paper cups, glass bottles (mostly beer & cheap wine) and all those wonderful things discarded by wonderful people over the winter months.
What is wrong with people? Is it that hard to collect it in a bag and pitch it in a wastebasket? It just seems like the right thing to do. But I guess not for some people (I'd like to use more descriptive language for them but I'll keep this clean - unlike the roadside )
Oh well there is not much I can do except just ask politely to please throw stuff away instead of just throwing it out your car window. Believe me I would like to just throw it right back in your car if I could !