Can I make an analogy to illustrate my view of this situation:
If I am driving my 4x4 at 70 mph (quite an achievement actually in this case...), and choose to turn the steering wheel quickly through two complete turns, then the vehicle will probably roll over and crash. If I do the same thing in my Mercedes 'C' class it almost certainly won't.
Now, I have been on an official training course run by the 4x4 manufacturer. At no time on this course was I told not to do this. However, it is up to me to know that I should not turn the wheel rapidly at high speed in this vehicle. If I do, it is not the manufacturers fault - they design a vehicle to do a certain job within a certain envelope. If I choose to take the vehicle outside that envelope then that is, frankly, my fault and the consequences are my problem, not theirs.
It is not an excuse to say that my Merc would not roll. They are different vehicles with different designers. As a driver it is up to me to know what the limitations of each vehicle are. Of course the 4x4 manufacturer could put in some fancy electronics to stop you doing this (perhaps a device that controls the powered steering according to speed). But, there is no need so long as drivers are sensible.
Of course, if the manufacturer told me that it was definitely safe to turn the steering wheel through two complete revolutions when it is not, then they would have to carry some (but not all) of the responsibility.
It seems to me that in the case of the Airbus A300, we have an aircraft that has been around for 30 years. Only one pilot has ever managed to snap the rudder off, and he did that by taking the aircraft significantly outside the envelope. It appears that he did that in part because his training led him to believe that this was an appropriate thing to do in those circumstances.
In this context, the fault just does not lie with the manufacturer.
So AA did not have this problem with their other fleets. Frankly, so what? The training for any fleet should be tailored to the needs of that fleet. Perhaps for the other aircraft types it was. For the A300 it appears to me at least that it probably wasn't.
Dr Dave