Years ago, just as it was becoming trendy for Muslims to wear hijabs etc I was in my local Sainsburys, doing shopping. There was a Muslim girl, not in a hijab but young and on the checkout, I'd seen her a few times and she always came off ok, fairly friendly.
She was serving a customer and suddenly whilst she was doing this there was a stand-up row, mostly started by the checkout girl from what I heard, which included a few phrases like 'how dare you disrespect me', and ended with a line about 'her being Muslim'. It seemed like the checkout woman had pounced upon a look or a comment the woman customer had said (I didn't hear this) and had just let rip. This young checkout woman was dressed in a Western fashion, with lots of makeup, manicured nails, big hair. The row got so heated and had lots of swearing, mostly from the checkout woman, that her supervisor had to come over and forcibly remove her as the white younger woman customer (guessing 30s?) was starting to get upset, not teary, but shocked at what had happened. The younger woman was denying she'd said anything offensive, said 'I was just trying to do my shopping'. I was just behind her in the queue.
I don't know what started this argument, but from how I viewed it, the checkout woman was spoiling for a fight and took a chance comment or something from a female customer to have a go. This was way before the hijab wearing became mainstream, at least in our area, approx. 18-20 years ago (gosh that sounds a long time ago!).
I think back then, that this was a sign of more radical behaviour amongst Muslims, it was post 9/11, 7/7 and our area was/is fairly diverse but is or was back then, white and lower to normal middle class (working class really as they all 'work').
I never saw the checkout woman again, and I'm assuming she was fired. I don't think shop work is easy though, customers can be rude, it was also at the time when customer service in general was going on the decline, e.g. in even a department store you'd get hardly any response from someone who'd served you. Me, personally, if I don't get a polite response when I've bought something, I won't return to that store, it's not about the master/servant equation but I expect a certain amount of civility when I conduct a transaction, rather than a grunt. The young man in the Greggs in Tescos (SW London) who made my tea and served me a vegan sausage roll the other day was lovely, polite, engaging, funny, probably had SEN/ND from my engagement, but was so nice, that I'd return there because he made an effort and was funny. In fact most of the Greggs workers are charming (apart from the ones in St James's Park area, a bit grumpy!) and that's why I return.