The issue at hand is not FedEx exclusive as I have been asked on several occasions to sign a separate form when picking up a package. I sign as I don't consider it to be a battle worth fighting. I then scan the package and as long as it gets an origin and transit scan I know that I am no longer liable for that package if it does not reach it's destination.
What Dano was saying is that many couriers will fight it just to fight it regardless of whether the consignee insists that they do it or calls in a concern/complaint.