Spork
I'm no expert but I'd think there is a "huge" difference between a rush bag and one where a passenger has simply not shown up after checking in for a flight. I think we've all spent time waiting on planes while baggage has been offloaded for a pax that has disappeared. I think everyone treats this as suspicious.
Rush bags are different, the pax can't really predict when a piece of luggage will miss a flight and, normally, they may not be able to predict which flight would subsequently carry such a bag. I still travel to places where baggage is dumped on the tarmac and you then have to point to your bag which is then chalk marked, I'm assuming it's an extra check and they still reconcile baggage to the passenger manifest...