Security theater - such a damn fail

I flew from Nashville (BNA) to Seattle (SEA) today. This isn't a huge and shocking turn of events -- people fly all the time.I had packed a few snacks for the flight to tide me over from when I left my house to when I got together with my friend. Again, this is perfectly normal.I even got super lucky and managed to get an exit row seat...While the seat doesn't recline...I don't think it's a worry since I could slouch all I could possible want.And I even though the flight attendants said this is a full flight, mysteriously the seat next to me was empty!But back to the snacks... I went rooting around my bag and I found something I wasn't expecting: a bench made knife that I had put in my bag when I drove from Seattle to Nashville back in March.What the actual fuck?This isn't a box cutter or anything like that, this is a fucking folding lock-blade knife with a three inch blade and carbon fiber scales. I put it there and promptly forgot about it until my fingers found it at cruising altitude.How the hell did it get through the X-ray machine?In other news, I know that I'll be mailing this back to myself from Seattle instead of trying to fly back with it.