Akro - I'm not doubting that the units are different. Your assumption was that international carriers didn't have an ADSB that worked in Austtralia. What I'm saying is all the internationals I've seen, based in Europe the ME and Asia do. In fact before the mandate there were more overseas aircraft with ADSB than Australian.
Do any US carriers into Australia fly outside the J Curve and ocean? If not, like the Springbok I mentioned, they would not suffer any penalty for not having it anyway.
Just thinking out load here, and call me a heretic, but if Europe, Asia, the Middle East and Australia have a difference with the US, just maybe its the US thats out of step?