'prison' and 'punishment' aren't synonyms. Make someone work their ass off to repay a crime IS punishment. As is locking them up, but by doing that, you severely decrease the chances of that person ever being a productive member of the society again.
Of course, should that person break the terms agreed upon, then I guess prison time is warranted as an additional punishment. And even in this case, with non violent criminals, in a setting where they can still work.
Prison is fantastically expensive, not particularly effective, and severely degrades the offender's life.
Restorative justice is much cheaper and more effective at fixing the offending behaviour, and the results of that behaviour.
Prison should be left for violent or unrepentant recidivists.