They could have forgiven the debt and come out ahead. Or they could have garnished his wages, or seized his assets and got their money while spending very little.
I think use of the police force to enforce private loan contracts is short-sighted based on the ham-fisted overuse of incarceration as punishment in our legal system. Interest rates are already built into the loan instrument to compensate lenders for the risk of nonpayment, while this practice is just kicking someone when they're down...
Isn't this pretty much the argument for law enforcement in general? I doubt it's ever "cost effective" to have police respond to say, noise complaints or minor acts of theft, but the goal is to show people that are consequences for breaking the laws or going against court orders.
Whereas kicking someone when they are down (i.e. already can't pay) is cruel and unusual, I agree that making an example of willful nonpayment makes sense, but that shouldn't be done at the expense of taxpayers(/no need for police involvement). That's why wage garnishment and other tools already exist for lenders to use with a simple court order. If the government foots the bill of enforcement, rather than the lenders footing the bill of wage garnishment intervention and court costs, then it will get represented in taxes rather than loan interest rates, which privatizes the gains (loan payments) and publicizes the losses (enforcement costs). The other side effect is that it subverts supply/demand based pricing of education based on student loan interest rates, which props up higher education price inflation.