I will be the first to admit we New Yorkers aren't known for our being overly polite. On the flip side, we tell it like it is. None of that fake southern backhanded pseudo-polite "bless your heart" stuff from us New Yorkers (unless we're being sarcastic or want you to know we're insulting you).
With all of that said, I can't stand when I say "thank you" while paying someone for a service rendered or a product purchased and they respond "no problem".
So, it's no problem for you to take my money and give me what I payed for? Well, I'm so happy for you! I didn't mean to put you out giving you my money.
I see the response of "no problem" to "thank you" as a rude step back from "you're welcome". How about "my pleasure"? I'm sure some witty sort (probably from Texas) might challenge me about expecting to hear a "you're welcome" after my saying "thank you". Such a person might say I shouldn't expect politeness in return for politeness. Well, sorry, but I do expect a polite response after I give you my money. If you are going to tell me "no problem" for taking my money, then just say nothing at all, that would be better. Saying "no problem" is fine if you're doing a person a favor for nothing, but not for rendering services or products that you charge money for.