In that section of the article they are discussing labor internal to the prison, specifically maintenance and daily chores. Yes, it is true, while in prison you

In that section of the article they are discussing labor internal to the prison, specifically maintenance and daily chores. Yes, it is true, while in prison you do not have a choice but to participate in that kind of labor and refusal will not help you be released early for "good behavior" or anything similar. External labor, the kind discussed here - contracted by a 3rd party for money - is voluntary.