I don't know what this means. He's being paid to faciliate the exchange of a customer's money for products/services, and to provide customer service when needed. In the case described, he facilitated the transaction and there was no service needed. So he was getting paid for doing exactly what his job required. Where does this idea that the customer has a "responsibility" to the cashier come from? It's not an equal relationship. Nor is boss to employee. Sometimes, that's just the way it is. It doesn't mean that customers should be rude.