It isnt sloppy
The OP stated a domestic flight - Qantas doesn't sell domestic tickets in the USA - or anywhere other than Australia
QF does not sell the domestic ticket on its US site - if purchased online from Qantas, it would be on the AU site with AU terms and conditions. When switching sites there is a confirmation box to click to accept that you are changing

The passenger wasn't even eligible for the benefit given that the passenger is not a Qantas member anyway and only applies to Qantas members - Other T&Cs are irrelevant given that there was no entitlement to the benefit

Disputing the charge is going to fail - even if initially accepted to pursue by the card company, Qantas will very easily be able to show that the charge was valid - this is something that would be for a court process if really thinking would have a chance of success