No one has mentioned my personal pet hate of our job: dealing with people using staff travel (whether staff or their relatives. The relatives are usually worse), who expect VIP treatment.
I can never get over how inconsiderate people can be. How can they be so rude to the operating crews by taking up their time with stupid requests and not bothering to clean up their own mess???
They should remember that the generous staff travel discounts come with terms and conditions, one of which is that their behaviour must be exemplary and beyond reproach.