After working on older vehicles long enough I think you can easily get "conditioned" into overlooking the obvious & expecting the worst...
My CCKW came home with a nice US marked brass padlock on the toolbox door. However, the shackle had been cut with a bolt cutter - presumably because the previous owner had misplaced the key. I was thinking about ways to fix it - which included taking it to a locksmith and pay to get a new key fitted.
Several weeks later, my seven year old nephew came over to look at my "new truck". He was up in the cab poking around and said: "Hey Uncle Bob, what's this key in the glove box for ?".
Boy did I feel stupid....
Best Regards...