That is to say: people who say that cats can't be trained probably think that because they have only tried to train cats like they're dogs.
Which, sure, training cats like you train dogs does work on a very small percentage of cats, because cats, like people, have a very wide range of interest and capacity. Some cats are very food motivated and are therefore very quick to learn the things that will get you to give them food.
Most cats, though? Have to be approached for training with the mindset of we will train each other rather than "I will train this animal." You have to observe the cat and watch what they do, and listen to them, and develop a lexicon of behavior-based communication based on the individual animal.
For instance: if Buster is sitting on the cat shelf and yelling at the bookshelf we keep the toys on, I know he's telling me he wants to play. We have trained each other to understand this interaction.
Phil, however, does not sit on the cat shelf and yell when he wants to play. He sits on the cat shelf and stares, (mostly) silently and meaningfully, at the top of the bookshelf. However, if he's on the cat shelf, but facing away from the bookshelf and/or laying down, he wants to be pet and loved on, not to play.
When I need to groom or medicate Buster, I can get out the bag of cat treats and set them in front of him, and he knows that I'm going to subject him to something undignified, but also that he's going to get a treat after, and he will let me do the thing (unless the thing involves touching his butt, which he hates and will always cry about).
When I need to groom or medicate Phil, he will run to his "safe place" (the cat tree behind the curtains in the bedroom) and make me follow him and attend to him there. If I pick up a grooming tool, then pick up Phil and carry him over to his cat tree myself, he knows what I need from him, and he will let me do the thing.
If I try to groom Buster without showing him the treat bag, or try to groom Phil when he's in a place other than his "safe place," they cry and struggle and sulk afterwards, even though I still give them treats. They need their own individual routine; I can't just put the treat bag in front of Phil and expect him to submit to my ministrations the way that Buster would, and I can't put Buster in the cat tree behind the bedroom curtains and expect him to stay put while I clip his claws the way that Phil does.
In conclusion: cats are good, actually!
