If I, as an adult, can clean up your poop for you, then it escapes me why you, homeless but also adult, can't pick it up and put it in a dumpster. The logical conclusion is that you do not wish to.
So, I'm not so sure that the baby/dog to encampment dweller connection makes the most appropriate vehicle for mentally dealing with the poop. Or, maybe, it is the right vehicle. I really don't know.
When I rationalize my poop scooping duties by juxtaposing them with the duties of parents and dog owners, I end up placing the babies, dogs, and adult poopers in the same category. I don't know if that categorization actually reflects reality, and therefore I can't tell if that kind of rationalization will actually help me react to the poop in a constructive way.