I do think prisons serve a purpose MN, but they have to focus on rehabilitation, especially for minor crimes, rather than punishment.

If you look at statistics for people in jail, most are poorly educated, impoverished, come from abusive or neglected backgrounds, have diminished mental capacity, etc. If you focus on educating them and turning them into productive members of society when they're in jail they are less likely to recommit crimes than those who aren't given any rehabilitation.

There's a lot of evidence to prove that prisoners who get their GED while in custody are far less likely to re-offend than those who don't.