Regardless of whether packages do get treated like footballs or not, I always double-box fragile items.

There is always a chance for packages to be accidently dropped or have heavy things placed on top of them.

I also take atleast a couple of 'progress' photos while I am packing the parcel so I have my own record

of how I packed the item and the type of packaging used (in case of any dispute) and then a last shot

of the sealed package complete with address label etc.

In the case of lodging an enquiry/claim through Australia Post I am pretty sure you would have to present

the package with its original packaging. In case a scammer conveniently got rid of some of the packaging

atleast my photos might show otherwise?

As for the 'option' of offering the buyer insurance, perhaps don't make it optional. If it is not a cheaper item

that can easily be replaced perhaps just cover the insurance fee yourself. Do it for YOU.