You are actually not reading that regulation correctly!
I deal with CASA regulation every day, and you need to read it, as it is written. For example... The regulation states...
(1) The pilot in command of an aircraft for a flight contravenes this subregulation if:
(a) the aircraft is fitted with, or carries, a radio; and
(b) the aircraft is flown by a pilot who is qualified, eligible or authorised to use the radio:
(i) for an Australian aircraft (other than a Part 103 aircraft or a Part 131 aircraft)—under Part 61 or 64; or
(ii) for a foreign registered aircraft—under a law of the aircraft's State of registry or the State of the operator; or
(iii) for a Part 103 aircraft—by a Part 103 ASAO; or
(iv) for a Part 131 aircraft—by a Part 131 pilot authorisation; and
(c) the aircraft is outside controlled airspace; and
(d) radio transmissions are not continuously monitored by:
(i) the pilot in command of the aircraft for the flight; or
(ii) another pilot who occupies a pilot seat during the flight.
(2) A person commits an offence of strict liability if the person contravenes subregulation (1).
Penalty: 50 penalty units.
So let's break it down....
If the aircraft is fitted with a radio, AND there is a radio qualified pilot in it, radio transmissions must be monitored. It does not say anything about missing the radio call It simply means that you must have your radio on and be listening! If you didn't hear it because you were sneezing, or chatting to your mate next to you, you are not in breach, of your radio is on, and you are monitoring transmissions. Nothing more, nothing less.