With regard to burying human waste in the ground - the point of doing so, to not less than a minimum depth and at not less than a minimum distance from water courses, is that the ground will provide a natural filtration function to 'neutralise' its effects. On the other hand, poo from animals, domesticated or wild, remains on the surface and water courses thereby get a much reduced benefit from 'neutralisation' by the soil (especially so when they poo straight into the water, or even choose to present themselves as a dead carcass lying in the water). It is a matter of scale - the amount of human poo in the wild, exposed or buried, will be trivial in proportion to the amount of exposed animal poo (and almost no human cadavers compared against animal carcasses).