 What seems to be a reason for many being sent to prison?
When you're in it, you don't much care what it is called; it is a place for punishment. She was in a detachment of three unfortunates like herself, convoyed by an irritable guard, climbing the steel steps toward Block O from the floor below, when she heard the yelling. The two guards turned to see what was coming in as the three new candidates for the Greensleeves slumped to a stop at the head of the stairs. While the fields were on, you could ignore the prisoners—they simply could not move fast enough, against the electronic drag of the field, to do any harm. They had spent so much time in prisons that it was sometimes hard even for them to remember what they really were, outside.
 people resenting the jobs they're assigned
 petty theft and small crimes  rioting over the rules imposed by the government  conspiracy theorizing  people resenting the jobs they're assigned