i think they do it to look polite but its also a time where its unlikely that ull ask them for something
Because they don't want a lengthy conversation, just a decision, a nod of the head, a point of the finger at the dessert menu, or the food sucks and you the need the Heimlich Manuever, etc.
Kind of like when the Dentist gets chatty when he's got his fingers in your mouth.
They're really not interested in what you have to say.
Or how they always refill your drinks when you are about to leave?
Because they are *******
They just do. There is no reasoning behind it....