Some hiding spots are better than others, but that one takes the biscuit. I never imagined there was such an adult version of Where's Waldo. Maybe I should have known better.
Just an interesting bit of history for a fairly ubiquitous idiom. I never even thought to ask about the meaning of "read between the lines" until I stumbled across this piece of information
All defenses fail, from time to time, which is why we generally employ multiple layers of defenses. When one layer fails there are others to pick up the slack.
Being in a safe environment is itself a defensive layer.