It's all the same.

So I've fallen of the no TV for the summer wagon. In the last year I have seen the same kidnapping ransom payoff scheme three or four times. The set up is that ransom is to be dropped off in a specific type of bag in a public space. Soon after the space is filled with people all carrying the same exact same bag. Maybe it's a bunch of kids in school uniforms with the same backpacks or it's part of a "flash mob" performance art piece. It's been done on Castle, The Unusuals, Rush (Australian show), and I think maybe one of the CSI's. It was also done in Leverage but it wasn't a kidnapping. I've tried to find out if this based on a really story or if all the cop shows just steal ideas from each other.