I successfully got 2 middle aged cats to do this. They have both since passed and I have two new cats. I haven't bothered to train them, but I think it's because my wife cleans their box and I haven't thought about it.

The first two cats did this almost effortlessly. They didn't give us any trouble because we changed steps slowly.

I believe you, sounds like a bit of a bother to train the new cats as well. Makes me wonder though if once one cat was trained, if you got a new kitten whether it could pick up the behavior from the trained older cat. That'd be pretty great - the gift that keeps on giving.

Cats exist that do this, and I haven't seen anything implausible from a cat psychology standpoint. Seems legit. Dogs can too

It's not a joke.

I've never tried it, but I've seen plastic products selling on the internet that replace the cardboard.