I've got an old lady on my route, and always has the side door open, when I call on the door, she just says come through the side door please, she doesn't even know it's me, it could be someone with bad intent. I understand why she does it, because she can barely walk. I should have told her, but I fear she is really stubborn, I'm thinking of giving the local comunnity support officer a call, so he can visit her and point out the danger.
Also, there are so so many people with windows open, it's not funny. Even if you put it on the vent setting, so there is a centimeter gap in between, getting a crowbar in between must be one of the easiest things, even if it's locked.