RNP-AR really comes into their own when there’s terrain or obstacles around. Not much of that happening in Burketown Morno, hence the minima you describe.
In the case of Paraburdoo with terrain around, an RNP-AR would be worthwhile and potentially knock a couple of hundred feet off the LNAV/VNAV minima. But a busted arse 30 year old Fokker can’t do them anyway so it’s not really relevant to this discussion.