Even if they did have a camera on board, it is not their business to pursue whoever took it unless it was the driver. While the situation is unfortunate, it seems that someone is just playing a game of 'finders keepers,' which is by no means illegal.
Also, I do remember reading a story recently about someone who was able to trace a stolen mac with mobileme as both computers were connected. If that is what you mean saying that the two are linked, then you might have luck using that feature if the thief has been stupid enough to keep that data on.
My post never suggested whose business it is. Calling the company to see if there is a video camera on-board would be a good course of action. If so, the video might show who grabbed the laptop bag. Evidence.....