That's a perennial problem. How do you connect the responsibility to the authority? The cashiers are the ones who have to face 30 angry customers, (face the responsibility) not the manager. (the one who has the authority to change things) Customers can complain to the cashier, but they have no authority. They can complain to the manager, but the manager is getting a portion of the money not spent on hiring full staff in the form of a bonus, so they're encouraged to ignore the complaint. It takes a certain critical mass of customers all spending less at the store before there's even a possibility of someone noticing a revenue drop, and no guarantee the blame will be put where it belongs if it happens.