Hard to swallow

YOU'RE in the supermarket shopping for dinner. It's been a long day and you want to make this quick. Into the trolley goes a plastic-wrapped tray of pork chops, vegetables, salad, maybe a couple of apples for sauce, juice, eggs and coffee for the morning, and perhaps some chocolate for a treat. Despite the bright lights, bad muzak and onslaught of packaging, it is a painless process and one that has cost you very little. Or has it?