Does this courtesy occur in the rest of Europe or is it primarily an American thing?
It's a British thing too. I have had it happen to me a few times in Poland, particularly if the shop is quiet. However, this combined with number 3, makes a nightmare.
I was standing in a queue for the 10 items-or-less when a woman walked to the front of the queue, only to be reprimanded by the cashier and the others in the queue... "But I only have ONE item!" she said.
Another thing which annoys me is the Polish inability to make a straight queue combined with female contempt for men doing the shopping.
I was in one supermarket queue with my wife when she decided to go and fetch some extra items. The old women in the queue adopted the "blob" formation, where you can't tell where the queue actually is, and then did that amazing thing where they don't appear to move but somehow end up in-front of you. Eventually one old biddy sternly commented.. "PROSZE PANA!..." about ME queue jumping. I snapped and ranted on in my bad Polish about how I had been there first with my wife BUT, if they so insisted, they could have my place and I'd go to the back.
Then they started mumbling, a little shamefacedly, to each other about "Oh yes, there was a lady there, wasn't there?" and offering me a place in the queue.
The "up-your-arse" scenario happens a lot in post-offices, especially when the biddy rests against the serving counter, huffing and sighing.
you take your position and that is how queues work.
YOU CAN'T BE POLISH!