When I was in schooling getting filled in on Web of Trust, I about ground that particular day's class to a halt because I couldn't imagine the world was that cavalier on such a thing.
Lo and behold, I realized shortly afterward it absolutely was the case, and there was nada I could do to change it except figure out how to get normal people universally fluent and invested in basic cryptography so they could manage their own trust networks. You can imagine how well that's gone.
