Right. They are just refunding it to those individuals even if they aren't having problems.That does not mean there have been 2.3 million users having problems with their adapters, simply 2.3 million people who have bought an adapter which Apple is (tacitly) acknowledging may have caused users problems and been faulty. Most of these users have probably never had a single issue with their adapters, however it is cheaper for Apple (and better customer service) to give them a few bucks instead of paying it to the lawyers to defend the action.
There is a truism in most legal cases that is especially in anti-trust cases: nobody wins except for the lawyers.
Same thing with cars: You don't have to have tires that are exploding, but as long as they fit the brand then you will get them replaced if there is a recall.