Good god, the number of times I've wanted to maim these ungrateful, impatient, know-it-all bastards. . .customers destroyed every ounce of faith in humanity that I ever had; having worked with legitimately insane people, the only difference I've found between my job as a public employee and as a retail employee is the pay and benefits, and I don't have to live under the stupid-ass philosophy of "the customer is always right."
And rather than stick up for their burnt-out employees, who have to deal with everything from insults to threats to actual violence at bare minimum wage, managers just kneel down and suck off whomever throws their temper tantrum. It's why people are so fucking spoiled now; they've gotten away with it elsewhere and they think that if they yell loud enough you'll be able to do something about the rules.