Supporters of this may believe that giving inmates jobs is a better rehabilitation device than playing basketball, working out, watching TV, or sitting in a cell all day. Instead, being taught to do things that most members of society have to do to survive.

Work credits could be seen as getting a shorter sentence by showing that you can behave like members of society (i.e. displaying evidence of your rehabilitation). They normally give credits like this for general good behavior, too (again, evidence for behaving in society, at large).