On a hot September afternoon in Sacramento, Calif., police officer Joe Bailey was leaning into the window of a crusty sedan, trying to figure out the common purpose of the six adults of mixed ages and races crammed inside. Inches from Mr. Bailey, a cameraman wearing a bulletproof vest aimed his lens at the passengers, while a sound man eased a microphone up to the window to catch the questioning.

"Is this the show 'Cops'?" asked a passenger. A moment later, someone in a passing...