The workers have learned that they can’t pre-judge the person knocking on the door; that opening the door opens a conversation, and that a conversation can only impact them negatively despite following the rules.

They know a belligerent Karen can cause more problems on a phone than they need, and that it’s easier and safer to play deaf until the person goes away so there’s no specific target for her rage – if she’s that kind of person.

But, as mentioned, they don’t know whether she or he is a Chad or a Karen, and the odds are low but the impact is high. So, best to play deaf and work another day.