Earlier quoted context omitted.
The point I'm making is that it's implicit that they are "not" criminals by virtue of there being such a huge discrepancy. This needs to be addressed in a clear, and concise manner instead of making sweeping generalizations about the discrepancy.
Who is 'criminal' is fairly arbitrary in many cases. Say you sell some hash to a friend. Legal in some states, can lead to 30 years in some others, generally not a huge crime in the sense of harming others.
Often, the DA will structure a plea bargain on drug or weapons posession (over a long list of more serious charges) because those are very easy to prove.
This idea that the prisons are full of good guys caught up in the system is detached from reality. Most guys doing hard time are guilty of about twenty other things that they haven't been prosecuted for.