Although they do feel pain, I believe they lack the parts of the brain that would cause them to remember it in a way to be traumatized by it. So they may feel the pain and struggle in the moment as a survival instinct, but I don't think they truly care about the pain in the same way that humans do. That is just my theory. Not sure if it's true or not. And after reading the article, they suggest that my theory is wrong. So I guess I'm with you. Not so sure.