This is already a reality in some countries. They not only detain a person, but they also freeze their bank accounts, social benefits, and salary. Essentially, the person may still be free, but without any money for who knows how long.

Moreover, they might deliberately cause physical harm, 'accidentally' breaking a leg or a finger. Of course, they will later compensate for the damage, but the amount will be laughable, and it will take a long time to receive the money.