A good friend of mine is Sherpa too, and used to do assist Everest mountaineers, he now lives in California. Kindest man you'll ever meet. He said he would carry gear all day long, and without shoes. I asked him once why no shoes? He said the mounters wouldn't buy them for him, so he didn't have any. Not sure how common that is, or all of the circumstances, but it did not sound like the mountaineers regarded him as more than a donkey in human form.