Except that the lock option would prevent cases I know of where someone clicked cancel when they realised theyd put something in tt, and it still tt'd it, or the other case where someone had put some ammo in the tt, and clicked tt, only for an object that hadnt been put in there, or that hadnt appeared on the to be tt'd list, to disappear and be tt'd, due to a weird bug.
Neither of these people were "retards", they got done over by bugs in the system, that wouldnt have caused the expensive loss of an item if the checkbox had been available. As it is when i go to a tt, i ensure first that all my valuable items have attachments with the exception of the fap which I'm extra careful with.
I believe I sent a support case along these lines some time ago, so with some momentum maybe something will be done
