Edit: As some comments have noted, this isn't a worldwide truism. My specific experience and question are pertaining to in the U.S.
I'm not sure it is. Are you referring to a specific culture or country?
I seem to recall there was a post regarding this phenomenon as it relates to car dealerships--something about the caffeine and its effect on behavior--on /r/todayilearned a week or so ago. I don't consider /r/todayilearned a source up to /r/AskHistorians standards, so I won't post it, but you might want to check there if you're still curious.