We had a couple back in the East US, and I was
really impressed. Not only were the cashiers faster,
but they tended to be happier - probably not just
wages, but management being good as well, even
well paid people aren't genuinely happy, if the
boss sucks.
As to chavs, I'm not so sure what they really are, but
there were a lot of lower middle class people there -
mainly blacks. They seemed to generally be better
mannered than what I'd see in normal supermarkets
though - even those in good neighborhoods. I think
that the extra effort of having to bring your own bag
or box things probably helped. Wider aisles, less selection,
made it all less intimidating. People came in to shop, and
buy, rather than piss around looking at everything.