In USA once you got criminal record, by default it stays for rest of life with you. Implications of that may be even more severe than actual punishment.
On the other hand in most of the European countries criminal records are limited and after X years they disappear and you can't legally discriminate based on that.
Some ppl will do something stupid at some point in their life and get a criminal record. Not giving them another chance is a major problem and actually can cause a lot of damage for everyone.