I strongly disagree that a cat using a litter box is in the same situation as, say, a circus elephant. Not even close!No, lisa, I'm not looking for pointers on cat care - I'm just trying to see where the line is for you. Most people who make such criticisms of animals in media don't view their animals to be in the same situtation, but they typically are. As a cat owner who doesn't use a litter box and lets their cat go outside, you give your cat a very unusual amount of freedom. Few pet owners do (and most veterinary professionals would actually say that freedom is bad for pets).
A cat using a litter box and a dog begging for a treat are in exactly the same ethical situation as the animals in the circus and SeaWorld, with only relatively minor variations in degree.
I go a few steps in the opposite direction, though.
A cat will use a litter box without the slightest prompting; it's instinct to want to bury their pee and poop and kitty litter is made to suit their instincts. A circus elephant lives its life chained, standing on concrete, traveling in cattle cars. They are forced to perform whether they want to or not.
The two situations are not even within sight of each other.