Here is what I believe to be the key point. From the original post.
"the crew in Philly mistakenly put someone else's dividend miles number on her account so she didn't get put on the upgrade list. Now, all the seats in first are gone."
I have a simple rule I go by.
My mistake: I pay. Example being buying a non refundable ticket and not being able to fly. Exception being medical emergency.
Their mistake: Airline pays!
The real issue then becomes how much time & effort do you wish to put in over something that will at best get you a voucher for a nominal amount? Based on the OP, US dropped the ball. Also keep in mind that if you as a consumer had made a similar mistake you'd likely be looking at a change fee etc etc. Just food for thought on a slow Friday