As a long time buyer, I really don't care if a seller chooses to use a courier or AP.....but I do care when they don't tell me which they use.  I now have a PO box as my address so if courier is used, I find out before the item is dispatched and can decide whether or not to proceed.  As Lyndal stated several posts above:

Shouldn't it be up to the buyer what service they want? They're the ones paying for it. Offer both. If a courier suits a buyer, they will select that option. If having their item delivered by AP into a parcel locker suits them, they'll choose that option. Everyone is happy then. Just make sure that if you do offer both that the courier option does say courier and not Australia Post Parcel with Tracking. Otherwise you could end up in the same situation as my seller that had to pay return delivery costs.