The existence or otherwise of 40kmh zones near schools is totally inconsistent. Some major roads do not have a 40kmh zone even though a school directly adjoins the road. In other locations 40kmh zones exist where they are unnecessary or questionable.
Schools Without 40kmh Zones
The following schools are at the intersection of the two roads indicated. In each case there is no 40kmh zone on the first-named major road even though the school gate is only a short distance along the side street from the intersection, or a gate leads directly to the main road.
North Ryde Public School has a gate opening directly onto the 6-lane, 70kmh Lane Cove Rd but there was no school zone on Lane Cove Rd. The school wrote to the RTA in March 2009 pleading for a 40kmh zone but the RTA refused.
On 12 May 2009 a child was critically injured by a wheel from a car while waiting for a bus outside the school. Had the speed limit been 40kmh instead of 70kmh his injuries would have been much less severe. Only then did the RTA install a 40kmh zone, but as with many locations it positioned the 40kmh signs behind trees so that they were almost invisible.
Does a child have to be seriously injured or killed at each of the above locations before the RTA installs 40kmh zones?

North Ryde Public - Gate onto Lane Cove Rd but there was no School Zone

Peakhurst West Primary - No School Zone on Henry Lawson Drive

St Joseph's Primary Moorebank - No School Zone on Newbridge Rd
Schools With Questionable 40kmh Zones
Compare the above with Mt Annan Christian College, Currans Hill. There is a 40kmh school zone on Narellan Rd even though the school is 800m from Narellan Rd on a side street. Narellan Rd is no busier than any of the above roads.

Mt Annan Christian College Currans Hill
Compare also with Padstow Park Primary, Padstow. There is a 40kmh school zone on Uranus Rd which is 360m from the nearest school gate. Uranus Rd is nowhere near as busy as any of the above main roads.

Padstow Park Primary - 40kmh zone on Uranus Rd 360m from school
The following schools also have questionable 40kmh school zones. In each case there is a fence down the median strip plus a pedestrian overpass. If a fence was added along the edge of the footpath it may remove the need for a 40kmh zone, reducing traffic congestion.
In the case of Fairfield West Primary School there is no entrance from the school to the main road, exactly the same as the first schools listed above without 40kmh zones. Unlike those it also has a fence down the median strip and a pedestrian overpass, so why does it have a 40kmh zone and they do not?

According to the Roads Minister the RTA bases its flashing light selection criteria on "crash history and risk, traffic and pedestrian volumes, speed limits, road environment and visibility".
The photo below shows the suburb of Bonnet Bay in southern Sydney. The indicated school on Tudar Rd only has 121 students. Tudar Rd only carries local traffic and virtually no heavy vehicles, yet the school has flashing lights.

Small school at Bonnet Bay with lights
The school certainly should have flashing lights, along with every other school in NSW, but how could it possibly have qualified for flashing lights ahead of numerous other schools that are on major roads carrying tens of thousands of light and heavy vehicles per day?