@Dr Mouse
"Leave it open, and leave unsecured shares on your network, with files containing all your personal details etc... you deserve to have your identity stolen, your important documents deleted etc."
No, it's still a crime to steal documents. However, you can't be accused of computer trespass.
If you left your car unlocked I sat in it and waited out of the rain, I have not stolen your car. You can claim civil issue over it, but the case will be thrown out because there's no damage. And any small amount that could be said ("He wore the seat out and listened to the radio!") were your own damn fault.
But the kid didn't steal any data, didn't delete anything and the 1's and 0's were unused and your own damn fault for making available.