I wonder where CASA are going to get all the staff to police this new rule. Wil they have an inspector based at every CTAF, to monitor all radio calls and book those that do not comply?
I can understand one of the reasons why overflying traffic should be monitoring the CTAF frequency, and that is the departure of a RPT jet. Normally, take off performance is such that in setting course overhead, the aircraft will be through 10,000'. If traffic are on different frequencies, it leaves TCAS as a primary collision avoidance aid, instead of the final back up. Throw in a lightie with a u/s transponder and the holes in the swiss cheese are lining up.