Surely you've all noticed? You'll be in a shop, picking your food for the week, it's time to pay (before you pick up any more crap you don't need) this is your chance, empty till point, you suss out your surroundings and glide in to the queue just before Gladys gets there with her tinned spam and cat food. You turn round and all of a sudden the queue is down the aisle - instantly everyone has decided now is the time they want to pay.
Just the other day I was in Marks and Spencer (Chelmsford, if you're interested) there was no queue so the shop assistants were re-stocking the shelves and arranging the mixed nuts (very important jobs), I toddled along with my roll and yoghurt, then all of sudden there was a swoop - FBI stylee, customers lined up behind me tapping their feet.
I've seen it on the other side of the fence as well, when I worked in Topman (Oxford Circus, if you're interested). Smile, scan, "do you have a Topman account card", pack, "have a good day". A manageable 2 or 3 customers, then BOOM! Snow ball effect, all the gays, (I mean customers) are lining up waiting to be served.
Why does it happen? People know how to shop, they know how to pay, it's not like they are waiting to see how someone does it in front of them - God, which way do you insert your card into the "chip'n'pin" machine? Do I give them the money or do they reach into my wallet and take it themselves? It's not rocket science.
Perhaps it's a comfort thing, why queue alone when you can be with others and work the queue? - "oh I see you went for the tuna baguette? interesting, I'm more of a pesto pasta kinda guy, do you come here often?". Maybe it's that human craving for company?
I feel sorry for the Sales Assistants in all of this queue craziness. One minute they're asking Mrs.Smith how her kids are, the next minute scan, scan, scan, scan, scan they go into panicked production line mode...NEXT! So people, next time you're in your local supermarket, bear a thought for the retail front line behind the check-outs. Think one in, one out.