This is allegedly a true story, told by the driver at his first AA meeting, according to the newspaper account.
From Herb Caen's column in the San Francisco Chronicle:
A motorist was unknowingly caught in an automated speed trap that measured his speed using radar and photographed his car. He later received in the mail a ticket for $40, and a photo of his car.
Instead of payment, he sent the police department a photograph of $40.
Several days later, he received a letter from the police department that contained another picture - of handcuffs.
Is the story true? If you want to know, head over to snopes.