Maybe there's a new fare category? Or it will just show on their screens that you elected the GO discount.

As for your last question, presumably it saves more than $10 not having to handle a customer's bags (it's -$10 total to take no bags, and $105-$175 PER BAG to change your mind, right?). It probably costs $10 just to check in a customer's bags, never mind move them around.

=aw