I think you will find there is no such requirement for a stationary vehicle to display a flashing light while working on the road. There may be a requirement to ensure a worker is visible and safe, but a camera car operator sits inside the car. In NSW, when the operator sets up the signs, the car has flashing lights going, likely complying with the WHS requirements.
Camera cars are parked off the roadway - either in legal spaces or by exemption. They do not block nor impede traffic. Cars parked on the side of the road are not required to having flashing lights.
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