So airlines still charged you for the federal tax they didn't have to pay during the shutdown

Let me reiterate.  If you flew during the FAA shutdown, the airlines charged you a federal tax, quite a hefty one in fact.  The thing is, the airlines knew that they didn't have to pay that tax as a result of the shutdown.  They were pocketing the money, but charging you for it anyway.  It's good to be king of a monopoly industry that cares nothing about its customers because the customers have zero alternatives for travel since every airline magically charges the same fare, to the penny, as every other airline for the same routes.