I can certainly understand how one can derive meaning from a trade or profession, but I would find it difficult to believe that anyone could really do that for menial jobs like a cashier or warehouse packer. These jobs are dead ends, they don't have a meaningful spectrum of quality and you're little more than a warm body.
A comedian (David Mitchell) once joked that he's proud of the UK's terrible service reputation. It doesn't seem honest or appropriate for service staff to be so happy and enthusiastic, why would they be? There's very little to be happy about.