A certain politesse definitely has a salutary effect on the smoothness of everyday social intercourse, but if I hear one more illiterate putz answer my "thank you" with "no problem" I'm going to
smash his face, tear his ears and eyebrows off, frog-march the bastard into the loo, and hold his bleeding phiz in the toilet while I flush it half-a-dozen times!!!! I regard "no problem" as improper.
You have my permission, sir or madam, to properly chastise any uncouth person who would use "no prob" as a substitute for "your welcome". Bad manners gets under your skin doesn't it?