Good question.
I got a late reserve reassignment to Deadhead to TUS one night a long time ago circa 2016 or so. Flight ran late and was going to depart after 3am. Customer service could not for the life of them get a boarding pass to print. It just would not accept me at all. They tried everything, calling scheduling and the NOC, finally the ops agent was standing there getting ready to close the door. Captain sauntered up and told me to hop on in, they would figure it out later. Good times.