You keep saying that and you are wrong. Bags are scanned off the airplane, by the airlines. The Disney barcode is scanned when they arrive at the sorting location. And it is possible they are scanned when they arrive at Disney. Disney isn't going to pay 5 people to scan 1 bag, they are to efficient.
It is also doubtful that the trucks are GPS equipped going out. I have been told by drivers they are not GPS equipped. Trucks are supposedly equipped because of TAS regulations going back to the airport, but even that has not been verified. The baggage transfer is very simple but efficient. There have been reports of lost luggage, but not much and I am sure if Disney was responsible, they took care of the folks. So you really don't have to worry about your luggage. It is being handled by a very efficient corporation and system.