Yes, the human race does include slobs. Unfortunately, we get to mingle with their residue, up close and personal, in the mountains.
It isn't just a problem with wag-bags, but with an attitude. It's the same careless, "it's someone else's job" mind-less, casual, sloppiness that we see everyday, from city streets to the backcountry. "No one will see it..." Out of sight, out of mind...duh.