Pet owners who don't pick up after their pets have no business owning a dog. Frankly, the owners who don't pick up after their pets are the ones who should have been on a leash during their younger years. They might have learned some manners and etiquette.
Having said that, society as a whole really should mind it's own business. Sure, we agree on the fact that pet owners need to be responsible. But what happens when we don't agree on some other issue. Generator hours, quiet hours, grey water, fire pit (where rules are not posted)... all can be disagreed on.
As a whole, it's best for campers to police themselves and not each other. Consideration goes both ways and the good thing is that we are mobile and can move. :)