[mellifluousmind]

It really depends on where you are from. If you are born and raised in Asia, or in urban America, I don't think you would feel comfortable leaving things unlocked.

Last time I checked, Windsor, Ontario, Canada has such a friendly neighborhood that they do often leave their home doors unlocked. Whether that's a good idea or not, it is up to you. Personally, I keep it locked, just for a peace of mind.