It Looked Legit
The manager was in charge of taking the dirty cash from his boss and putting it into the restaurant’s system to make it look “clean.” His “friends” brought the dirty cash in a suitcase each week to be mixed in with the restaurant’s cash.
It worked for so long because the waitresses at the restaurant worked hard to retain customers, so the business was legitimately turning a good profit. However, the profits still weren’t enough to explain the manager’s flashy parade of new cars.