I don't have any theories about missing planes. Except for the obvious logic that the Earth is a big place. And I know how difficult it is to find lost things around the house. So it's not surprising to me that planes can be lost.
But my immediate thoughts about your post don't actually refer to flying. Because you reminded me of a story from my sister last month.
She is planning to take her grandchildren on their first cruise. But independently, 2 of them immediately voiced their fears, having watched The Titanic. So she asked why did everyone remember The Titanic?
Because there was only one of them!
OK, not strictly true in the history of maritime disasters. But it was enough to put their minds at rest.
!BBH