It didn't happen to me, but I saw it myself. I also work at retail, so I thought this would be great to share.
I went to post office to get the criminal record for my job, because I have just applied to a new job. It's kind of a new thing in my country for some years, but that's not important. Normally you wait at the post office around 15-30 minutes, no big deal, because it's afternoon after all.
Also when you go to post office, go to the machine box, you choose from options what you need on tablet, it prints a number, you take the paper with a number. When your number is on the screen, you go to certain counter that screen is telling you to go to. Back to the story. I am sitting patiently, listening to some music and looking at people walking in, because I have no other job to do.
Then this lady in her 70s came in, sat down and was waiting 1-2 metres from me. Now it's been 20 minutes since she came here. She started looking rather irritated by the waiting. I was just thinking " oh boi, somebody is going to get it.". The lady (let's call her IL, as Irritated Lady) stood up and was cutting in queue.
She went to one counter and the conversation went like this:
IL: how long is it going to take? I have been waiting here for 20 minutes and I only need to pay for something! You people called numbers after mine! You called 390, 391,392,393, but not mine - 389!!"
Postman behind the counter:" I am sorry madam, but the number doesn't mean the order. It depends on when the paper with number is printed. System divides people's numbers into sections of our service. Some of the counters can't do the same service as other counters, because they aren't specialized in that kind of service. I am sorry, but you have to wait until your number is on the screen".
The IL murmured something about how long she is waiting, but walks away.
But she started doing it to every counter my post office had! They all said the same to her. What a crazy woman.
I stood up and went to talk to her:
Me: I am sorry, but everybody is waiting. It doesn't matter if you want to pay for something small. I have been waiting here even before you came in here. So please just wait. You don't have to make their (postmen's) day worse. IL: (started screaming at me) how dare you speak like that to elders?! You are rude. Your parents did bad job at raising you.
Me: Yeah, maybe, but unlike you at least I am not rude to working postmen and being incredibly impatient. So whose parents did worse job at raising?
Then she began shouting again and I just told her "have a nice day", started listening to my music again before my number was on the screen (like one minute).