No you shouldn't have to tell them, but if nobody else has ever told them, you would be doing them a big favor to do so. If schools & families aren't teaching this stuff (and many aren't), where is the person going to learn this stuff? TV? They probably have no idea of what they don't know.
When I think about the sheer quantity of students in my program who have NEVER held a job, EVER....it would not surprise me to hear that they need this info. Besides the ones who have never received a paycheck, EVER, there's even more who have done jobs like doing research for professors - but never anything professional or even anything where you're required to be somewhere 8-5. It's almost disgusting.