I think it's the training set.

Pretty much every organism with a brain has a sophisticated survival reaction to physical contact with any part of its body, because its brain is trained on nerve signals. Everything with eyes or sonar learns spacial awareness of objects and their proximity, velocity, directoion of motion. I think the clue is that biological brains are trained on a physical world with very complex rules and physics as well as reactions that arise from chemistry.

Words and images, audio and video, even virtual worlds with soft-body physics, are just flat projected shadows of the complexity of the actual world.