Here in Belgium it's usually the other way round.
I've had a checkout woman talking to her colleague the entire time while scanning my items and taking payment, without once making eye contact, saying hello or thank you.
Yep it works both ways, several times I have been in a shop and am seemingly an inconvenience to the sales assistants' busy social schedule. At least they were serving you and taking payment rather than just standing around having a chat.
I don't think it is unreasonable for staff to chat amongst themselves during quiet period but when there are customers queuing up it gives a bad impression.