Seems like we get too much of one extreme or the other
Incompetence...the security guard who walked off his post because he just wanted to "stretch his legs a little", the dolt who forgot to plug in the metal detector, the guard who just waves you and your carry-on through the checkpoint with a bored, annoyed look on her face, etc.
or
Wildly overzealous security...the onboard security agent who tackled a poor guy in the aisle who merely wanted to go take a piss before the plane began its descent.