Animals are wonderful to have around, but they're also a lot of work. As the person responsible for maintaining clean litter boxes in this house, I know of what I speak. I'd like to imagine it as an act of love for them, but even I can't fool myself with that. It's just stinky and gross and necessary.
But the cats aren't completely reliant on us humans. Left to their own devices in the wild, generally speaking, unless they're as pampered and hopelessly domesticated as our furry little royalty, they'll get by. And at the least, they'll never miss litter boxes.
Farm animals, however, need their humans just a bit more and it's seldom been as evident as with a sheep named Baarack.