I don't reserve it for low-paid workers. I say that to anyone who wants to talk to me with whom I do not wish to speak.
I actually came up with it back when "day trading" was a big thing and self-styled financial geniuses would approach me at Starbucks to pitch their services.
Their pay has to do with it because they're not being paid enough to compensate them for having to additionally deal with people's snide and cynical answers to a simple question which they could answer politely and more straightforwardly.