Actually I think society does understand, or at least we used to. This is exactly why there is a separation between juvenile and adult criminal records. Regardless it’s all the more reason why your information should be your personal property.
Imagine for a second the prospect of an infinite record on everything you have ever done. According to Holman Jenkins, Jr. who was quoted by Marshall Kirkpatrick in a recent article in the ReadWriteWeb
[Schmidt] predicts, apparently seriously, that every young person one day will be entitled automatically to change his or her name on reaching adulthood in order to disown youthful hijinks stored on their friends’ social media sites.
I suspect that Schmidt thinks that this is like having your criminal record purged when you turn 18, but why exactly is it a good thing that I might be “entitled” to change my name (which I can do already if I wanted to). What I should be entitled to is the option to ask Google to delete everything they ever collected on me. The only question is will they provide this willingly or will we have to require them to?