As someone who collects on delinquent child support...
Jail is a powerful motivator. I've never actually gotten anyone jail time. By the time that sentencing hearing comes up, I always have money in the bank or an acceptable proposal for a payment plan.
Which suggests the people who actually end up in jail probably cannot actually pay the debt.
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From the SigmaTo the K!
Polyamorous, Pansexual and Proud of it! It Gets Better