aviation_enthus,
Go to Katherine Library or Historical rooms and look for a book on Conellan Airways and have a look at their route network in the 1960 and 70's throughout the NT, Western QLD and North West WA using everything from Cessna 180's, Beechcraft B18's, Beechcraft Twin Bonanza's, Beechcraft Queenair's, de Havilland Heron's, DC-3's and later Fokker Friendships.
Lots of other operators in that part of the world had some interesting route networks carrying passengers, freight, mail etc.
Operators such as
Ord Air,
John Beers Aviation at once stage had an RPT run from Perth to North West WA in a Baron,
Arnhem Air,
AirNorth had extensive RPT throughout the NT operating Cessna C310/ 402/404 /441 from the mid 80's.
Civil Flying Services at one stage had an RPT route Perth to Alice Springs in a Metro,
Hazelton likewise had very extensive RPT network using C310 and PA-31/350 through NSW.
The old thing money, punters and a hundred and one other things to keep it all running and profitable. When things are going good in the bush people travel, but when things are quiet and people don't travel services are lost.
Both TAA and Ansett extensive operations through regional areas such as QLD, WA, SA and NSW. TAA operated Queenairs and F27's on regional routes in QLD, Ansett operated Piaggio P166's between Alice Springs and Ayers Rock, on SA routes and also on QLD routes.