I'm deeply skeptical that training AI on (effectively) thousands of images of one horse will perform very well at training to recognize horses in general.

I'll double down with you on this.

Then train the AI using a binaural video of a thoroughbred and see if it can distinguish a draft horse and a quarter horse as horse...

Are you suggesting that if a group of kids were given a book of zoo animals before going to the zoo, they would have difficulties identifing any new animals, because they only have seen one picture of each?

I think that's an interesting question, and a possible counter to my argument.

Certainly kids learn and become better at extrapolation and need fewer and fewer samples in general as they get more life experience.