If you have less than 30 minutes fuel, then declare a mayday and land.
Brilliant. Annnnnd then what....
The majority of airports across the country that can cope with an RPT aircraft have AvTur on hand.
But not every GA airfield / ALA across the country has Avgas. If I have the choice of an unscheduled landing with 30 minutes reserves at West BurrumButtock (where there is no fuel) or continuing ahead to land with 20 minutes reserves at BurrumButtock (where there is fuel).....well then I know what my decision is going to be..
And here I am using the example of two airfields relatively close together. What are the options when one really gets in the great outdoors such as when traversing from Forrest to Coober Pedy, or from Warburton to The Rock?