Therein lies a big part of the problem; it's been discussed in the last few pages about how it could be made more relevant to the towns along the route. If you were going to use it you would have to be available on one of the two days that it actually works and unlike the bus you can't just rock up - it has to be pre-booked. Really for anyone living in those towns Stateliner, the V-Line Bendigo-Adelaide bus or Firefly would have to be the better option?
For reference, the former Passenger Transport Board, now known as (insert actual name here) actually has stipulations protecting regional area contracts, part of it is in return for providing concession fares.
Between Adelaide and Mount Barker, services are provided by AdelaideMetro.
Between Mount Barker and Tailem Bend, services are provided by LinkSA.
Between Tailem Bend and Bordertown, services are provideed by Premier Stateliner.
VLine & Firefly are permitted to operate through, but may not set down leaving Adelaide, or pickup Adelaide bound. Premier Stateliner is bound by the same rules in LinkSA territory, and LinkSA is bound by the same rules in AdelaideMetro territory.
It is permissible for a passenger travelling to Bordertown from Murray Bridge to board a Premier Stateliner service in LinkSA territory. I do not have to travel via a LinkSA coach on its rare service to Tailem Bend then change.
A similar thing applies between Adelaide and Coober Pedy, and I may be a little off, but I'll do my best.
Between Adelaide and Virginia, services are provided AdelaideMetro
Between Virginia and Balaklava, Port Wakefield & Kulpara & into the Yorke Peninsula, services are provided by YP Coaches.
Between Port Wakefield and Port Augusta, via Highway 1 & via Bute & Pt Broughton, services are provided by Premier Stateliner
Between Port Augusta and Coober Pedy, services are via Greyhound on their Alice Springs service.
For reference, Virginia is a little unique in that you can actually travel on the YP Coaches bus to Adelaide, as well as use AdelaideMetro, but you pay YP Coaches rates, not AdMet rates.
For example, if I am travelling from Virginia to Port Augusta, I do not have to travel with YP Coaches to Port Wakefield and change buses.
If you want to see it visually, you can download the map here: http://www.adelaidemetro.com.au/bussa/pdf/bigmap.pdf
PS. If you don't prebook, the bus typically will not stop for you. In the major towns, you can just turn up before departure and get a ticket, but if you are at locality on the route, say Dublin, you must book or the bus will bypass you. If they don't have to detour, they won't. Also if you pre-book, you are normally guaranteed a seat on the bus.