They must be held responsible while you property is out of your hands.
Absolutely they should!
The best system I've seen so far is where you are given a plastic laminated number corresponding to the one on the box you are given that you put your stuff in, and you hang on to that as you walk through the detector. You then don't get access to your box on the other side until you produce the number to the person waiting there with your box.
Seems to work well, but as someone said previously, the best method is to just stuff everything into your carry on bag (if you've got one).