This is has been discussed many times on the forum, and of course is explained on GSX manual too: the airplane you are flying doesn't have any effect on the choice of ground operators.
It would be wrong if it did, because ground operators are local to the parking, not to your airplane, if they were tied to your airplane, unrealistic situations like the one you indicated, of being serviced by an australian crew at KLAX, would happen.
The only thing in GSX that IS linked to your airline code (provided the airplane you are flying has an atc_airline_code set in the aircraft.cfg ) is the choice of Pallets. Those, instead, are supposed to be linked to your airplane, because if they were tied to the parking code, you would end up seeing pallets unloaded on arrival with a different livery than those loaded on departure.
This means, GSX ground operators are then correctly linked only to atc_airline_codes of parking, and assigned with the scoring system, as explained on the manual.
