At work, I try to always say "please" and "thank you" when I ask someone to do something. It doesn't matter if I'm asking a student, or asking staff. Even though I'm supposedly the supervisor, I still politely ask "please" and "thank you."
Just for the heck of it, I kept track of how many times I overheard one of the instructors using either "please" or "thank you." In the seven hour day, I heard these words used exactly three times.
Please don't try to convince me that it's a cultural or generational thing. The truth is, it's just bad manners.