This reminds me of an episode of Seinfeld:
Kramer tells Jerry that a bank will offer anyone $100 if they are not greeted with a "hello" by a teller when they enter the building.
At the HOME FEDERAL SAVINGS BANK Kramer walks up to a teller.
Kramer: Hey!
Teller: Hey!
Kramer: Hey! wait a second. You didn't say hello.
Teller: Yes I did
Kramer: No no you didn't ...Hundred dollars.. I get a hundred dollars.
Teller: No, No I said Hello.
Kramer: No, No You said Hey!
Teller: Well.. Hey! is Hello, same thing.
Kramer; The ad said that the bank's gonna pay a hundred dollars if you are not greeted with a hello
Teller: You're taking that much too literally. Now sir , do you have any business to transact.
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What do you want? Acknowledgement? You call out their parents because people use a different expression?
I choose the old fuddy duddy answer.
"You're welcome" "no problem" whatever. I sometimes say "It's no bother." Even a short "Oh, sure."
We don't dress up in a suit to get on airplanes anymore either, and I like that better.