Protect and serving might get in the way of role call arguments about whether or not you should call the people you are arresting "hoss," or "boy" or "son". Wiseman's nice little touch of including Nixon's speech shows that those white hat waving folks don't know what the fuck they're cheering for.
The police before the Almighty media. Today everything would be filtered through "communication". Scary how free and self confident those Kansas City policemen feel, knowing they are being filmed, never trying to act in front of the camera. Genuine violence and ordinary racism. Maybe the best first hand document captured by Wiseman.