It’s because they can then fit the red tag security system
http://www.amaray.com/
We don’t use it here but perhaps Australia does. The Americans of course had tags inside the case which can trigger alarms at the door. The red tag system can’t do that – it just makes it really hard to open the case if you steal it where as here of course, they remove the disc from the case (which I don’t particularly like)
Seems like a pretty reason from my point of view but I guess Australia is a bigger market and we have to get our stuff from them