I've wondered about that too – it's really common around here. I can only tell you how it's happened that I unwittingly contributed to it a couple times, as fpllows:
Usually, my dog would poop early in the walk. And I didn't want to carry the bag of poop with me the whole rest of the way if I didn't have to. So I would leave it on the side of the trail with the plan of picking it up on the way back. Then, a couple times, I totally forgot about it until I was all the way back home.
We need an app: "Dog poop reminder".
I'm all for finding a stick & flicking it into the woods. Putting something organic in plastic wrap and then in the trash seems counter-intuitive assuming a rural setting, like a woods run/walk.
NYC, say, doesn't offer such an option. Not even wooded parts of Central Park, I suspect. But people will be people :-).