When you say leave the door unlocked, do you mean while you are in the house or away?
I encountered this when someone was talking about where I live as being the kind of place where you could leave the door unlocked. Everyone thought that seemed overstating it because you'd only really do that if you were going out for a few minutes. We were quite shocked to hear they were talking about locking the doors while they were home. None of us had even considered that as a meaning even though it was the norm for where they came from.
I encountered this when someone was talking about where I live as being the kind of place where you could leave the door unlocked. Everyone thought that seemed overstating it because you'd only really do that if you were going out for a few minutes. We were quite shocked to hear they were talking about locking the doors while they were home. None of us had even considered that as a meaning even though it was the norm for where they came from.