Exactly. I have no idea. It would make sense for a large, capable predator to try out eating a human, but they just don't. Maybe humans don't have enough fat on them to be appealing? ...but orcas also eat birds, which don't have a lot of fat. Maybe because orcas are intelligent collaborative hunters, they have instincts not to eat other intelligent species like humans? ...but orcas also eat dolphins, which are similarly intelligent hunters.

I would also expect any large predator to spontaneously act aggressive at times, but this very rarely happens. Or at some point I would expect it to make a mistake and kill a human even though it doesn't actually want to eat him/her, but this has apparently never happened.

I find it all very interesting, but I'm at a loss to explain it.

Orcas seem to have fairly specialised diets -- there's different subspecies, each of which eats something different.

https://seaworld.org/animal-info/animal-infobooks/killer-wha...

>Type A whales eat mostly Antarctic minke whales and have also been observed hunting southern elephant seals.

>Large type B whales eat mainly seals, especially Weddell seals, and also hunt minke whales.

>Small type B killer whales have been observed hunting penguins and are believed to mainly eat fishes.

>Type C killer whales mostly eat Antarctic toothfish (Dissostichus mawsoni).

>Little is known about the diet of type D killer whales, however, they have been observed preying on Patagonian toothfish (Dissostichus eleginoides) caught on longlines.

So if type C whales don't eat seals and type B whales don't eat fish, it's not surprising that no whale type likes to eat humans -- they're apparently just picky eaters.