I am department manager in a hyper market and I outright "overlook" customers just yelling through the aisles or just show their phone in my face with a picture of a pixelated image of a Tabasco bottle. Form a sentence, say hello and goodbye, then we can talk. It is my daily routine that I often say "Good morning first" and then continue with the customer's demand and it often makes them realize how poor their human interaction is. Just yesterday I had some grump lady going "hello.hello?hello?!!" within like 2 seconds and I asked why she'd yell like this and if she'd address staff instead of randomly yelling, she'd get better service. Another thing is that we stopped handing snacks ("things on a toothpick") despite we are actually supposed to by company rules, but after seeing people grabbing five or six and then tossing the toothpicks into the shelves and others requesting - not asking! - that we prepare freebies made us stop. I will be blunt, but my 15 years in retail and 5.5 years as manager, I turn more and more into a cynic misantrophist. . .
But in general, you mentioned that you are British and manners mattered. I will tell you the truth, but this is my almost life-long experience: Many folks, especially macho folks (Arab countries and Kosovo) have their boys taught to be demanding and loud. We have many Ukrainian refugees, they are equally demanding and unbearable, demand in their langauge (I have Ukrainian workmates so I know what they say) and are generally loud and make a fuzz if nothing goes their way. The old German ways of humbly asking is gone since these folks get more population and they raise their kids the same they've been raised... Since I am 11 I observed this in my school with lots of migrants, it was a real culture shock from the ~95% German suburb I came from. Being threatened with violence if you didn't share your chocolate was a common thing. Go figure how people behave now, especially in times of trash media like Facebook, Reddit and Twitter...
The other thing is gratitude. I have it that way: If you have something I'd like to have, I am the one demanding. And I am absolutely on the mercy so to speak if you actually do what I request. That means I am being polite and glad that someone else spend their time to get me something I'd never get without the other person - ChunYinZi comes to my mind; we had dozens of PMs and it felt so good to have nice conversations and learn about each other. And now, 94% of my library is High Quality thanks to him. It is amazing what a nice journey it was. I am sure if it'd just grung "GIMME DAT" I would not be that lucky.
I've donated $10 to Retromatic in one of the albums as another, non-verbal but monetary form of gratitutde.
I am born 1990, so I am still kind of tangent of the next generation and their overall attitude, but I can't. I have nice trousers, Olymp shirts and wear a jabot (yes, and I love it!) And then you see people in smelly jogging sweaters that can't even form one single sentence and devolve into grunt language. This is overall also blending into this forum, more or less.
EDIT: Oh, I see what you mean by that! Well, the two members that might be addressed.. I think both are very young. In fact, one is 14 years if I remember correctly and the Polynesia fan has a revealing "Location" line... Heh, I must say it made me smile how you taught some manners.
