Mr. Monk Goes to Jail - S2-E16
Plot hole: It is unrealistic that a prison cook who did not punch out would not be missed or found until the next day, especially after a lock-down scenario as portrayed in this episode, where a meal has been poisoned - likely in that very kitchen.
Answer: The two men are trying to work out a secret deal between them without involving the union, which means the workers' interests aren't being represented and defeats the whole purpose of a union. The mayor would lose labor's support and Cusack's union troubles would just be starting.
Captain Defenestrator