Also, in reality, i do not think he would have gone to prison at all. I mean where is the evidence of his murders? Norton had all the evidence stacked against him for the money laundering, but as for Hadley's murders? Unless Hadley outright confessed i think there'd be very minimal evidence to convict him.
Exactly, it's not like Andy would have been around to testify against Hadley and if he was his word as an escaped felon would carry little weight. In reality Hadley at worst would have been suspended pending investigation. Hadley being cuffed and stuffed into a police car makes for a more exciting climax and that is what the producer wanted there.