It's inconsiderate to make other people cover your work shift
Erin was given tickets to see her favorite band live, but she has to work at the restaurant that night.
Erin wants to see the concert.
Erin talks with her coworker a few days before the concert to get her shift covered, so she can see the concert.
Erin calls in sick at the last moment before her shift to be able to go to the concert.
Erin's coworker who needed the extra money can work the shift and no one has to change their plans at the last minute.
Erin's coworker has to stay to cover her shift and then her coworker has to cancel her dinner plans with friends who are moving out of town.