Originally Posted by
Superguy
If they're safe enough to give away or sell, why aren't they safe enough to take on the plane to begin with? It's ridiculous.

Because the one isn't necessarily related to the other? Of course, most items are not a danger for the plane itself but a danger to the other passengers on the plane. It's a confined space. You can't just move away if someone loses his or her nerves and runs amok. Someone running amok with a knife can certainly overpowered, but probably not before several people are hurt.
HTB.