So there's the opinion of Dr. Eugenie Scott, who is a well-qualified physical anthropologist, and then there is the evidence. I can't explain why Dr. Scott thinks as she does, but her opinions are not the deciding factor, nor are the opinions of any single expert or textbook. If we must rely on expert authority, then it is best to rely on the consensus of expert authority, which weighs heavily on the side of human "tails" being tails without the quotes.
I think the whole debate hinges on this excerpt.
If one doesn't have to interpret it as a tail, and it's down to a "consensus", then really it's up for debate.
If it's down to induction, most tails, from what you say, aren't tails.
Are these "real" tails? I still have no conclusion on that because different people tell me different things.