That thread should go some way to explaining it. It's only the most recent example and no doubt there would be far more like it if Wilpena was open slather to all. Worst part is that as soon as anyone hears "Wilpena" and "aircraft crash" the immediate assumption is that it's one of the scenic operators (see the first post in my link above) Not good for business that's for sure!
Wing Root, given that I know Wilpena's strip isn't normally available to anyone other aircraft than their own, what other assumption does one make? Prangs CAN happen to any aircraft - the fact that they belong to the owner/operator of said strip doesn't make them immune!
DF.