I expect you have all seen it on your runs or walks. A bag of dog poo left below a tree: someone thinks they have done their duty by scooping the poo into a bag, but can't be bothered to take the bag home. So, to the minor environmental hazard of leaving dog poo, they add the much greater environmental damage of leaving plastic in the woods or fields. Do they think it will magically disappear?
And what do we do when we see it? Do we pick it up and take it home ourselves, to protect our environment? Or do we just suppress our outrage as we run past, maybe justifying this to ourselves by considering the moral hazard of allowing the irresponsible minority among dog-owners to think it's OK because someone else will pick it up? I confess that I am in the latter category; what about you?