There's also the trick of rooting through the store garbage for receipts, then going through the store to find the corresponding items and 'returning' things you never bought with the found receipt.
Returns are mandated here though and I guess the US is anti-consumer in a lot of ways so companies won't really be forced to find solutions that don't explicitly benefit them.
Of course if you only allowed returns strictly with proper receipts all your challenges shockingly disapear except the all the people that are pissed off because their return is denied instead of only the minority now.
I really don’t think Australia has this solved any better than the US, if this is the only solution.