What about firewalls, ID (Intrusion Detection) systems? I think we can make a similar argument about them.
Another side note, have you ever come across a situation where you cannot keep the lunch packets or any other food items from your co-workers in an office or classmates in a school? One crude way to do that is to take a bite and keep it :-) it'll surely act as a deterrence. A good way to have it packaged as if it's not a lunch packet - most hungry people won't bother to open that. This sandwich bag seems to be a good idea as well (though won't work after others figure out your trick)