I think that politeness requires that when you are a patron in a restaurant, you make eye contact with the wait person and say "thank you," when they bring you something or take a used dish away, and that you make eye contact and say "please" when you ask them for something.
FWIW, when I go out with someone I don't know very well to a restaurant, I watch how they treat the wait staff. The way they treat people who they know have to be polite to them and cannot respond to rudeness or discourtesy tells me a lot about what kind of person they are.
Courtesy is something that is always good and never wasted. When in doubt, always err on the side of courtesy and politeness.