People don't mind being *asked*.
What they mind is customers who go off on them about "liberal conspiracies" and in general act abominable.
Convince your pals to stop doing that, and the damage will be reversed.
Of course, if they believe that the proper way to treat clerks is as servants in a world where the customers are petty tyrants, there's no help for it. I bet servers spit in the bottoms of their ice cream cones before adding the ice cream too. Bad behavior has all kinds of unintended consequences.
