I had a think about two scenarios. Do UA pick up pax ex SYD to MEL when they are doing their shuttle between the two cities? Im quite sure they aren't allowed as that would constitute cabotage but their crews are allowed to operate because it is a continuation of an existing international service. Could qantas do the same thing? Yes because they are allowed to pick up domestic pax and the they do.
Could the QF flighties get off the the 747s in LA and operate a UA domestic service because they might be cheaper than the UA crews? Absolutely not.
Jetstar are entitled to operate their international flights as domestic tags there is also no question about that. If the cabin crew are not Australians nor do they have the legal right to work here in oz, then it is certainly a matter for immigration to deal with. They do have asics, I have seen them, but if they come through customs and immigration on a gen dec then I cannot see how Jetstar can then on-sell that flight as domestic tag as it is no longer an international service once it has cleared customs and the crew are therefore operating as illegal workers, if the company is selling additional seats ex the international port of entry to wherever domestically.
No wonder the govt is taking a very dim view and customs has asked jetstar for a please explain, I just wonder where the FAAA stance is on this.