I used to work at a post office and you would be AMAZED the sort of stuff that people wrap things in! Blankets, garbage bags covered in tape, cloth, old book covers, etc. If it can be turned into makeshift packaging, then Aus Post has probably seen it.

I remember one specific example a few years ago where an elderly lady had wrapped a package for her grand-daughter in giant palm leaves (and a LOT of sticky tape). When I asked why she did this, she said they had fallen off her tree and she didn't know what to do with them so she wrapped her daughter's gift in them. We had to accept it. Technically there is nothing against the rules saying you can't pack your parcels in giant leaves. I hope her grand-daugther got her package safely.

Recycing packaging is common by comparison. It wouldn't even raise an eyebrow.