A couple of weeks ago, I was standing in line at a manned till in Sainsbury's. The checkout area supervisor approached me, waving vaguely in the direction of one of the DIY tills, and asked me if I would like to go there and scan my own shopping. I politely informed her that I would not, unless the store was going to offer me a discount for doing the till operator's job for them. This raised a small cheer from other shoppers, and left the supervisor looking non-plussed, before scurrying off back to her lectern..