I can't remember the last time I signed for an article delivered by Australia Post. I'm thinking maybe about 2 years ago.

It's all contactless now, so signatures on delivery are made by the Australia Post employee.

If they don't know the receiver, they should ask for identification before delivering the article. Then they will sign their device on the receivers behalf.

If your buyer thinks he's going to successfully challenge the proof of delivery based on the fact that the Australia Post employee signed on his behalf, he'll find himself on the wrong end of that "gotcha moment" he can feel coming on.