What customer service?

I visited Pick & Pay Farrarmere this morning to buy items for my business. When I got to the paypoint, the cashier just sat there with no customer in sight. I was then told the customer was not finished shopping, although some items were already charged for and packed in bags, but not paid for. I left my goods and walked out, sourcing a better quality of goods and service from Spar. The question is, according to what arrogant logic does the cashier and the customer believe, other customers have to wait at the paypoint for a customer to finish their shopping, while other customers are ready to pay and go?