Indian Casino

context: the police waits for the "cheater meter" (for parking) and the narrator says about one of them when seeing him in action:

"You should see this guy work the slots at an Indian casino!"

I understand they are talking about the slot machines, but what is special about Indian casino?
Does it have any meaning?

Thank you

Although gambling is illegal in most US states, certain areas reserved for Native Americans (Indians) are governed by local NA councils who make their own regulations. Quite a few have opened very lucrative gambling casinos.