Well the cost of the admin team would be pushing it. But more importantly, if we want to talk unfair, is when I say the cost can be charged to the employee, that is the choice of the employer. From a management perspective, the cost is so minimal, that i do not see the sense.
The legal costs are borne bythe employee. Although, as you point out, that is harsh, because teh person is in trouble, the garnish order, being a judgement, is only after all other attempts have been made. That is the employee has ignored calls and letters and has made no attempt to settle the debt. One cannot run away from problems, they need to be dealt with, taht includes being in debt.