He didn't even have the 'common courtesy' [=he was not even as polite as people can usually be expected to be] to say goodbye when he left.
He picked up the airport 'courtesy phone' [=a telephone that customers can use to call the company that provides it] to call for a car.
They paid a 'courtesy call' on the ambassador. [=they visited the ambassador because it was the polite thing to do]
(..) Your staff. You would not part an old man from his walking stick. My lord, Gandalf the Grey is coming. He's a herald of woe. The courtesy of your hall is somewhat lessened of late... ...Th'oden King. He's not welcome. Why should I welcome you... ...Gandalf Stormcrow? (..)2002 The Lord of the Rings: The Two Towers