More than $91 million is owed in reparation by offenders nationwide.
But victims' advocates say authorities are not doing enough to enforce the repayment of outstanding money.
Reparation can be ordered by a judge under the Sentencing Act 2002 if a crime victim suffers harm, loss or damage.
Sensible Sentencing Trust founder Garth McVicar said when reparation was introduced as an alternative to prison sentences, the legislation lacked the teeth to ensure it was paid.
"We are appalled at what we have seen happening, because the warning signs have been there for some time.
"Ultimately, if you are going to use reparation as an alternative to sending someone to prison then it must be paid."
Having a soft hand on reparation enforcement sent the wrong message to offenders who "could give the fingers to the system, walk out of court and basically laugh their way to the bank", Mr McVicar said.
Ministry of Justice spokesman Nigel Fyfe said collecting reparation was the responsibility of courts. Court staff seek payment in full in the first instance then negotiate sustainable payment arrangements where appropriate and take enforcement action when necessary.
Enforcement action includes clamping vehicles, seizing and selling property, making compulsory deductions from people's income or bank accounts, issuing arrest warrants and preventing overseas travel.
The courts' powers were enhanced following the passing of the Courts and Criminal Matters bill last year, Mr Fyfe said.
Since the introduction of the Credit Check of Fines initiative in February, overdue fines and reparation can now affect a person's ability to obtain credit.
From November 2013 a further incentive for people to pay will be introduced, allowing for a person's driver licence to be suspended if they have unpaid traffic-related reparation or fines. The Justice Ministry has also made improvements to how it data matches with other agencies to obtain contact information for people with unpaid fines and reparation.
