“Do you understand why they do that, though?”
It doesn’t matter. You see, we have this thing called “civilization”, and one of the ground rules is, we don’t model our behavior on that of animals. Well, at least that’s how it used to work.
Hence my comment that if a dog is well-fed by a human, they won’t resort to eating vomit or feces. They will, however, almost always consume their placenta.