What then? If they're not forced to produce something of value to give to you, then how can you ever be made whole again? Does the state pay? If so, why do taxpayers who didn't commit a crime foot the bill? If it's insurance, then why do non-criminals paying insurance premiums foot the bill?
If there's nothing linking the action (_theft_) to the needed outcome (_restitution_), then there's this unmoored loop of perverse incentives wherein some folks can continue to commit crimes with very limited consequences.
Doesn't mean that everyone should be forced to work while in prison. But surely for any and all crimes that have a clearly defined dollar amount, shouldn't that criminal be forced to pay that amount back? Garnishing future wages can be circumvented (_just don't get a real job when you get out, keep stealing things to support yourself_). And even at best, it's very much _delayed_ restitution. Justice delayed is justice denied.