And in most cases, the MFS pumpers are not allowed off the bitumen, so in a 20-40 km radius of the City, they become relatively ineffective, due to not being able to access areas the fire is going in. (A fair potion of the hills face zone - that is the hills to the East of Adelaide, around 10-15 km out of the city is National Park, with dirt tracks).
Add to that a high concentration of CFS brigades within the 20-40 km radius of the city, generally with appliances more suited to the off road stuff than MFS, then MFS don't tend to respond with a large number of appliances.
However, they do seem to be used for asset protection in the urban / rural interface (also close to the city!) where they can park on the bitumen road & plug into the mains......
Pip