I actually think supermarkets are a great way to groom our young folks for the real life skills of the working world as it offers them their first customer-facing experience in a high-volume and sometimes hostile environment - such as an authoritarian manager or the "customer from hell." Thus you learn how to handle difficult people and other adversity with a smile on your face.
After my supermarket stint, I went to work in a restaurant - which was the major leagues of "customers from hell'! Also, I'm pretty sure the chef there was a young Gordon Ramsey, or one of his relatives.
LOL! So true. (And a great education.)