etudiant
Autopilot is out of my area of expertise, but as I noted in a previous post, Boeing did develop an autothrottle 'split' warning.
No idea why it wasn't implemented fleet wide - I've seen much 'lesser' fixes mandated by AD. Then again, given all the other ques that this crew failed to notice, I don't think it's a given that another que that something was wrong would have made much difference.
The real question remains - why didn't the crew notice? Were they really that asleep at the wheel, or was there something else going on that was distracting them (e.g. the pilot incapacitation that occurred on TAROM). Unless they find the CVR, we may never know.