Last I was there (wilpena) I spoke with the CP about using their strip instead of Rawnsley Park.
He listed quite a few valid reason's.
1. Strip Length
2. Normal Density height. (IIRC all his a/c are turbo)
3. Limited Parking for 'visitors'
4. Lack of insurance to cover visiting aircraft.
The 2 he didn't mention, were, Rawnsley park gets a/c traffic and landing fee revenue, and when Wilpena Resort come and get you, they get to charge you a transfer fee............
Rawnsley is a good strip, and the accomodation/meals are pretty reasonable too.
Jas