These criminals need to be dealt with swiftly and aggressively. Jail is necessary because you don't want others thinking they can get away with it.
Jails are full of people who stole things knowing that no one would catch them. Most deterrence based crime prevention philosophies assume that the person doing the crime thinks he has a good chance of getting caught. As I'm sure this guys friends said to him "No one will find out".
And once caught once what little deterrence there was is lost as far as a second criminal act is concerned.