My wife visited her grandparents in western Pennsylvania some years back. They were going out to lunch, and being the last one out, my wife locked the door. When she mentioned this, her grandmother said, "I hope I have the key". She routinely left her house with the door unlocked!<p>Myself, I have a dog. I got to test the dog recently, when a locksmith was replacing the ignition switch on one of our cars. I kept waiting for him to finish. Finally, I gave up waiting for him and went to use the can. Of course, that's when he finished, and came in looking for me to pay him. The dog made it very clear that the locksmith was <i>not</i> coming any further into the house. It didn't attack him, but it drew a clear line on the floor: you go no further.<p>So, we lock our doors, and there's the dog. Anybody who gets past that has to worry about whatever I find handy. Lime-Away? Really good chemical warfare agent in a handy spray bottle (but it's almost like a gun, you can blind someone, so you'd better be <i>sure</i> before you pull the trigger). That tool for unscrewing supply hoses from the bottoms of sinks? (Good for jabbing or clubbing, light enough to get good velocity, heavy enough to do some damage.) Even a cat can be thrown, and will hit with claws out looking for some traction. Think. You've got way more weapons in a house than you might expect.<p>Now, would I consider that adequate in some situations like Mandatum's in South Africa? No way. But for where I live, it's probably good enough. (Or maybe I'm just cocky because I've been lucky.)