It's a curly one. MOS139, the Aerodrome operators regs, stipulate that non-safety critical issues are not normally subject to NOTAM (to avoid overloading the NOTAM system). As such fuel availability is not normally considered a NOTAM subject, as it is not safety critical. Like parts of aprons being unservicable. An annoyance certainly though. It also something that the AD operator is not directly responsible for so may not be immediately apparent there is a problem. That's why there is always a fuel contact number listed.
However, in the intro section of ERSA where the decode of the facilities is located is this:
29. HANDLING SERVICES AND FACILITIES
29.1 Replenishment facilities are listed using the following codes. The left hand column contains the code symbol, the main body gives a brief description and where applicable, finally (in brackets) the Australian designation.
CAUTION: Due to changes without notice, accuracy of REPLEN entries under “Ground Services”, cannot be guaranteed. Airservices Australia takes no responsibility for the accuracy or completeness of refuelling information. NOTAM will not be issued notifying changes.
My bolding and underline.