Ultimately regional South Australia suffers from a small population, a small economy and relatively short and road friendly distances to Adelaide. If you want to know why South Australia has virtually no regional freight or passenger services these days, here's the statistics showing the primary reasons.
Largest regional cities/towns in South Australia (2014 ABS figures)
1. Mt Gambier; 28,649
Road distance to Adelaide - 434km
2. Whyalla; 22,464
Road distance to Adelaide - 381km
3. Murray Bridge; 17,582
Road distance to Adelaide - 76km
4. Port Lincoln; 15,879
Road distance to Adelaide - 647km
5. Port Pirie; 14,319
Road distance to Adelaide - 223km
6. Port Augusta; 14,288
Road distance to Adelaide - 305km
7. Victor Harbour; 14,218
Road distance to Adelaide - 83km
Gross Domestic Product for Regional South Australia in 2013 was $24.7-billion
Now compare this to regional Queensland where the largest remaining concentration of regional rail freight in Australia is to be found...but notice how despite their size, the cities closest to Brisbane produce no rail freight.
Largest regional cities in Queensland (2014 ABS figures)
1. Gold Coast; 551,705
Road distance to Brisbane - 77km (produces no rail freight)
2. Sunshine Coast; 330,498
Road distance to Brisbane - 118km (produces no rail freight)
3. Townsville; 189,287
Road distance to Brisbane - 1354km
4. Cairns; 153,566
Road distance to Brisbane - 1701km
5. Toowoomba; 149,102
Road distance to Brisbane - 125km (produces no rail freight)
6. Mackay; 121,909
Road distance to Brisbane - 967km
7. Rockhampton; 118,043
Road distance to Brisbane - 633km
Gross Domestic Product for Regional Queensland in 2013 was $158.3-billion