It's really strange to me that the City Council has to place stickers on bins in an attempt to persuade people not to leave their rubbish lying around.
I remember many years ago being astounded at the way a fellow passenger dumped her empty soda can half absent-mindedly out of the train window. So I guess there's my answer - it's for these "absent-minded" folk that we pay taxes to have stickers asking them to be nice and not litter.
Oh, and then don't get me started about the plethora of cigarette butts you'll find lying around public areas... heck, we don't even smoke and one of our outside plant pots has become a resting place for many discarded cigarette butts - thanks guys. ;)