It's not that Australian airports are cheapskates, but there is always a trade-off between spending money on installing the kit and the cost of delays and diversions. In a nice sunny country like Australia the number of days when you can't land in Cat 1 conditions is relatively few and it is cheaper for all concerned to put up with the occasional delay than to shoulder the cost of installing and calibrating the higher Cat airfield equipment, not to mention the cost of equipping the aircraft and training the crew. In the UK it is claggy much more often and the economics are different.
The other side of the equation is the availability of diversion airfields and their weather patterns.