At what point do you realize that this is wrong when you're building it? I'm so lazy that if I showed up to do the job and found out that I only had the equipment to make this faulty door, I'd still just go through with it. No way I'm dragging myself all the way back to the job site just because I was given the wrong material. They can figure out how to use the door themselves.That, my friends, is how things like this happen. Pure laziness.
I guess this works well if you want a door that only locks or unlock from the inside. Even if the person had a key they couldn't get in, nor could they pick the lock effectively. The kid from Home Alone needed one of these doors. He would have been perfectly safe, or should I say, the robbers would be perfectly safe. They were the ones who got the short end of the stick in that movie.