I think only because federal law doesn't allow it. Dr. Ingrid Visser in New Zealand snorkels with them. The joke my dive buddies would have for anyone who didn't go on a dive trip was "we saw orcas".I guess no one jumped in the water to swim with them
I skip out on a trip to Neah Bay, and then I get messages from multiple people about orcas. I'm like "GTFOH, who says exactly that BS line?"
Then I get the pictures. One of my buddies surfaced next to a pod that just ignored him.
I recently spoke to someone who ran into them when diving, and he didn't enjoy the experience. While I like the idea of seeing the true apex predator of the ocean, I'd probably soil my undergarment and dry suit so badly that I'd have to throw them away.