I'm struggling to figure out what value AA thinks they're getting out of this fairly random approach to compensation (versus consistently compensating people for delays of a certain magnitude). Are they expecting to get more out of the PR value of people praising their generosity than they would be just making everyone affected feeling better?

My girlfriend has had a pretty bad summer flying pretty regularly between NYC and the West Coast, with something like 80% of her flights delayed by an hour or more, and nearly all of those delays caused by mechanical issues rather than weather (including one five hour delay that sounds like it included much ineptness by the JFK ground staff). One of the few flights that made it on time nonetheless involved a mechanical problem that ended up with the firetrucks surrounding the plane upon landing. Despite all of these misadventures, she's received no acknowledgement of the considerable inconvenience from AA. When she reads Flyertalk over my shoulder and notices people getting big batches of miles for isolated incidents, she ends up (justifiably in my mind) irritated.

Is AA just hoping that people that have been delayed won't hear about others getting compensation? If so, it seems like a supposition at odds with any PR effect they're hoping to get out of the random approach.