Had a chat with our local delivery guy and he claims that the guy is just plain lazy and abusing the rules.
He has to make every effort to deliver the parcels even leaving them in a secure place if available and leave a ticket in you box saying where he left the parcel.
Our local guy reckons the ones you do not deliver waste time as you get back and have to sort them out and log them into the book for pickups so you may spend an hour doing this instead of getting back filling out your sheet then going home.
Stick it right up the guy who is abusing the rules and see how long he lasts, most are contractors and there is a clause there for aus post to get rid of him if he does not follow the rules.