Every time that I leave the house, I have to have a death grip on my keys. If I'm not white-knuckling those suckers, I ain't going nowhere.
This isn't due to some bad past experience or anything. I am just cripplingly afraid of locking myself out even though it has not happened once in my years on this planet.
Although I actively avoid leaving the house when possible, the sample on my leaving without locking myself out is still pretty robust. So, why, then, do I have such a big paranoia?
Part of it's because the ramifications of getting locked out are fairly significant, so I understand it from that perspective.