It seems we as the reader, or through the thinking of the narrator, we are found with unanswered questions, and wanting more information. The narrator, Oskar, often asks questions, such as "Why is there gravity?", and he never gets an answer. Or when he is trying to find the thing in Central Park based on his dad's clue of no clue at all. As a reader, we are still unsure of how exactly Oskar's father died, and why he talks about the things he does, such as his Jujitsu class, or giving the key to the mail woman.
There are several unexplained events in the novel, including the doorknobs and the keys, also including the reason why Oskar's father was in the World Trade Center when it fell. The book is "designed" to let you figure out these questions on your own.
The doors and keys actually may have somewhat of an explanation. Recently we learned that the grandfather has been watching through keyholes, and I Oskar states that his father was there because he had a meeting.
"Well, what I don't get is why do we exist? I don't mean how, but why." I watched the fireflies of his thoughts orbit his head. He said," We exist because we exist." "What the?" "We could imagine all sorts of universes unlike this one, but this is the one that happened." (13)
The reason the Unexplained Events motif is under point of view, is because as a child, Oskar is very curious, yet his knowledge is limited and adults tend to ignore or not fully answer him. Thus all we are left with is unexplained events.
(16) Title: Why I'm not where you are 5/21/63. (108) Title: Why I'm not where you are 5/21/63. (208) Title: Why I'm not where you are 4/12/78. (262) Title: Why I'm not where you are 9/11/03. I found it interesting how four titles are the same but with different dates.