It comes down to: who do you trust?
Sure, the 'system' is not perfect. There have been some pretty big failures of the 'system' over the years. Yes, I will admit that the various 'good guys' involved are sometimes not very good at all.
Still, it's the system we've got. If we're going to simply assume that every con's tale of woe has merit -or, worse yet, simply assume the con was a victim of circumstance- then we are granting the con greater virtue than the judge, jury, procutor, policemen, and victims that accused him. Open court is the only forum we have where both sides have a chance to persuade a dozen strangers of their case.
That's why I said 'believe nothing.' I've seen serial, violent, child-molesters claim their jail time was only for 'back child support,' and I've seen 'spitting on the sidewalk' convictions used to imprison violent psychopaths. It's worth noting that when a local dope house was closed down, not a single one of the dozens of convictions had anything to do with drugs. The criminal justice system is as foreign to you and I as Wonderland was strange to Alice.
Perhaps the only real answer, the only 'workable' solution, is to practice some 'tough love' and let these eight-balls work their way out of the holes thay've dug. There are plenty of deserving folks asking for a 'first' chance. Let the 'oops crew' suffer through a few years of temp work, menial labor, etc., to prove their merit anew.
At the risk of being accused of lacking respect for fellow trades .... those familiar with me know better .... I'll state the obvious: there are other trades that are richly populated with convicts. Roofers, drywall, and concrete work are three that come to mind. Oddly enough, there is also value in an electrical candidate having some skills in these areas. I submit that a few years of such experience just might remove (for me) any stigma of a criminal conviction.