Unfortunately it could happen to anyone anywhere. Obviously the Australian media isn’t reporting on the others, but the same group that breached Qantas also recently got into M&S, Harrods and Co-Op in the UK, then WestJet and Hawaiian Airlines, and several insurance companies in the US. They previously breached Visa, Ticketmaster, Louis Vuitton, Nike, T-Mobile, and Vodafone in the US.
I think there’s an assumption that in-house staff wouldn’t fall for the scams because they receive better training and just generally care about their jobs more, usually because they’re higher paid and higher skilled than the outsourced staff. I’m not sure how true that would be in reality.