Because Australia is big with not very many Air Ambulances. The UK is small with plenty of them.
I couldn't put it better than 'ropes away' from the thread covering the 'other lot'
"My advice to anyone thinking about donating money to this would be to think again. There are far too many air ambulances already and the addition of a dedicated airframe just for flying one group of patients is simply not needed. In fact, it's not the airframe that has to be specially adapted, most existing aircraft are suitable--it is the experience that the medical team brings to paediatric care that matters. Whether you are in an air ambulance, SAR helicopter, MCA helicopter or even a fixed wing aircraft, the medical team brings the expertise and equipment with them.
There is far too much duplication of effort regarding HEMS services and adding another airframe to the mix does little more than diverting valuable charity money away from those organisations already supplying services. It's really weird that most people look at the helicopter as the ultimate life saving tool when, in fact, it's a combination of a flexible transport platform and the team it brings that is the true life saving tool.
Bottom Line: save your money and spend wisely."