They were Black and driving a dark colored Caprice not white guys in a white van. So they would have been dismissed as kooks.
Have you seen the Comedy Central show called "Trigger Happy?" The creator of the show (a British man) pulls off a stunt where he is walking down the street dressed like a bandit, holding a big sign over his head that says "THIEF", and he is walking to his car, which has a big sign reading "GETAWAY CAR" on it. He only rolls video when there are patrol cops walking by, and they can be captured on video. The cops won't/don't even look his way!