A brain teaser, Two robbers took everything they could get their hands on. A police officer saw it but did nothing to stop them. Why?

They were at an all you can eat Chinese buffet, and the restaurant was encouraging customers to eat as much as they could, so the two robbers piled as much as they could into their plates, and weren't put off even though a few of the local police officers had showed up for some reasonably priced Chinese food too.