Yesterday I went to the big Leclerc in Bergerac to do my 6-monthly looroll shop, there were about 2/3 of the tills open & all had queues.
A manager-type person (with her arm in a huge complicated splint thing, no skiving there) came past as I approached the tills, saw me and my 384 loorolls, said "is that all you've got" & I said "no I have a couple of edible things too" & she took me to a closed till, opened it & sent me through the check-out. No waiting at all.
So they aren't all mean & grumpy & unhelpful. I haven't yet met a till-operator here who is (MG&U), that said.
(I bet I'd be vile to everybody after a while if I worked in Leclerc etc, but then my idea of utter hell would be working in a supermarket in whatever capacity. I'm sure not everyone works there by choice, or gets the hours that suit them, etc.)