My father, an inveterate Costco shopper, has a half-joke about this, because also the cashiers will routinely inquire if you "found everything OK?" He says tha

My father, an inveterate Costco shopper, has a half-joke about this, because also the cashiers will routinely inquire if you "found everything OK?" He says that this is actually a threshold poll, and if too many people respond "yes" that triggers the Grand Reshuffling of Merchandise overnight! I actually think he's exactly right. Why does a cashier care whether you found everything? You're already checking out, it's too late to go hunting for more, and the cashier can't be the one who could help you look. So it's not an invitation to customer service, it's simply gauging your satisfaction.