I think that there is an intersting divide here, that meshes nicely to "lock/no-lock", which is mostly attitude/fear based.  The no-lock is: "meh, its not worth worrying that much about" and the lock is: "i must lock my doors, im afraid of being robbed".<p>Personally I feel locking is partly a totemic ritual, involving more magical thinking than people are willing to admit about it. Seriously ask people why they lock the doors when they have a giant window right next to it, and they say "its safer" and "it keeps out the burglars". Point out the window, and they say "it just works ok".