I’ve heard it explained that “hey” used to be more of an urgent way to get someone’s attention, rather than a casual “hello” like it is now, so it sounded rude to some older folks.
The point of language is to communicate information.
If the information was successfully relayed, the language exchange was successful.
If the person knows you MEAN “hello, I would like two of these items here, thank you good sir. hands cash and cashier says thank you You’re welcome. Have a pleasant day, sir” when you SAY “Sup, two please. Thanks man. No problem have a good one.” then you have successfully languaged.
So when my wife with a plethora of issues involving word recall says some insane thing because she can’t remember the right words, as long as I understand what she means, her language did it’s job.