[vidarh]

Especially since it's a blatant security lapse: Put something through the x-ray, leave it there, as the staff is used to things waiting around for a while, and then walk away as quickly as possible before the bomb you left in it [1] blows up the checkpoint and everyone waiting. They're providing a convenient way of dropping off explosives and leaving them that reduces the chance of a guard noticing you intentionally leaving something behind and reacting.

Then again, we know very well by know that these checks does not have much to do with actual security.

[1] I have no reason to believe they'd react to a bomb with sufficient urgency to stop anyone from walking off. I've left bottles of liquid in many times (by accident), and they don't usually notice. They have noticed my sons game console (was bringing it with us to his grandparents and didn't think to take it out of the carry-on), but it's not like they reacted with any urgency - they just put it aside and waited for us to come over and point at it before dealing with it.