I don’t understand the comparison with QF. I don’t think they have any fares with restrictions on lounge access. Even Jetstar flights allow lounge access for their own FFs.
QF’s international guesting policy (only for QF members) is that the guest must be travelling on the same flight as the cardholder. This policy on BA would go a long way to mitigate the guesting issues reported here.
However, for QF domestic flights, your guests do not need to be travelling with QF (or at all), and WPs can use the lounge anytime on the day of the flight.