1340
Nobody says it anymore
(startrek.website)
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.
"No problem" takes "You're welcome" and implies that it was of no inconvenience to you either. But I understand that older generations find it important that service workers be most humbly at their service, and adhere to a strict social etiquette just short of "Yes, m'lord" and "Shall I suck upon your dick, sir?"
"You're welcome" is more appropriate in a professional setting, but if you're getting your jimmies in a rustle over someone saying "No problem" to you instead, you're a bit of an assfuck.
I don't think either phrase is impolite. Good manners are a made up thing. If someone said 'thanks' to me and I said 'tiddle dee dee' I'm not being rude, just a bit weird, nobody's honour has been questioned, I haven't said anything that could be taken as an offence.