Speculation here: when the idea of SBAS was pitched to the government, their first question most likely was; “Who will benefit and who is going to pay for it?” Farming yes, but the union won’t let their members be charged for it, union is too strong. Same for the trucking association. Ok, increased rego charges for all vehicles? Political suicide. Maritime? Maybe. Aviation? Absolutely, and ASA offer to recoup the installation and running costs via their Nav charges process, plus a small percentage for themselves.
okay then, the argument is made that aviation is the major beneficiary and should therefore pay for the system.
Speculation at this time, but I’ve seen this exact process before to justify a pre determined decision