Here's another aspect: I don't know how it is at the John Wayne airport, but I recently departed from the Omaha airport on United, and over there they physically searched all the checked bags PRIOR to the customer checking in the luggage, and they were TSA checkers not United employees. Presumably, if something were found it would be returned to the owner as this was still a public unsecure area and nothing had been turned over to the airlines yet.
Apparently, at John Wayne airport, the bags are checked in first and then an American Airlines employee goes through the bags, confiscating what they don't like and refusing to return the property as it has already been passed through security.
I guess the lesson is that it is less of an airline policy and more of an airport policy, depending on which side of the security line that the bag is searched.
-PJ