I'm having trouble understanding how an ARFF facility can be justified when a tower isn't. And why there are towers at locations without ARFF?
Because the establishment of ARFF is a CASA requirement
based on passenger numbers, not aircraft movements.
MOS Part 139 Chapter 2: Criteria for Establishment or Disestablishment of ARFFS.
Why is AsA providing the ARFF? Quite simply this should be the responsibility of the airport like some other countries.
The rest of MOS Part 139H details the standards required for ARFF, which if you take a look, will explain why an AD OPR would not want to do it themselves.
https://www.comlaw.gov.au/Details/F2...l/Text#param40