Well my office is in the lost property section of a local bus company. The amount of lost property that gets returned is phenonminal. We have had people ring and say they have lost mobile phones and all sorts and I would say about 90% get returned. What amazes me is that many people ring up and say they have lost their wallet with say $500 in and its all the money they have etc. They do get returned with all the money still in it. It really restores your faith in humanity.
Having had my wallet stolen and never found I would hand in anything I find and have always done because I know the anxiety and heartbreak etc it causes when you loose something. Recently I lost my mobile phone but someone found it and returned it personally to me. SO there are some wonderfully honest people out there.
I guess sad to say there is also some very dishonest people out to, who never stop and think about the consequences of their actions. It is usually lost by people who can least afford to lose it. Even if there was no return address I would still turn it in to the police just in case someone looks there for it!