Do all 3 serve a single station though? I can't see a station in the photo, and AIUI most railway in rural Australia is predominantly freight-only.
Yes, Gladstone does have a passenger station which was served by all three gauges in its heyday.
There were three stations on the Port Pirie to Broken Hill line in South Australia which were triple gauge for a time. All three are now only standard gauge, but they are served by the Indian Pacific and The Ghan and also the location of full-length passing loops on the east-west transcontinental route.
Gladstone: narrow gauge 1876-1927, narrow+broad 1927-1970, triple gauge 1970-1990, standard gauge only from 1990
Peterborough: narrow gauge 1880-1970, triple gauge 1970-1988, standard gauge only from 1988
Port Pirie: narrow gauge 1875-1937, triple gauge 1937-1970, broad+standard 1970-1982, standard only from 1982
There is abandoned dual gauge track at all three of these towns, preserved track and a triple gauge turntable in the Steamtown museum at Peterborough, and the National Railway Museum at Port Adelaide has some dual/triple gauge track including the reconstructed full triple gauge turnout from Gladstone.