Firstly, the ship was stationed within 5 miles of the centre of airway A59, which the A300 should have followed. Given this point, there was every possibility that an airliner would fly over.
Secondly they saw an A300 and thought that it was an F14. Based on an incorrect reading of their radar they also thougt that the plane was descending when it was in fact climbing.
Thirdly, the radar display on the cruiser registered a Mode III transponder code, (which suggested a civilian aircraft).
The USS Vincennes was an AEGIS cruiser, which is designed for AA
use, if this is the best that they can do, what about a ship not designed for this role.
Quite how you can conclude that Shit happens in war is somewhat baffling.
I suggest you read Aviation Disasters ISBN 1 85260 602 9, particularly the section relating to the comments by the Captain of the USS John Sides.
If an Iranian cruiser had shot down a US airliner, would you view be different.