I've flown with a couple guys like this, and I don't know if your guy is the same type, but both of the captains I flew with that were like this just didn't care about the job. It wasn't just PAs, it was everything.

If that's the case, then they can't be fixed. They have to fix themselves, or they will eventually quit. Just take it upon yourself to make sure things get done, and hope you don't have to fly with him/her again. If you get stuck with him for more than one trip, talk to him about it, and see if that does anything. If not, perhaps a call to pro standards is in order.