No, it's neither of those things IMO. (I've driven a lot in Australia and in the US.) The latter you mentioned sounds like a truck-specific rest-stop - there are loads of those on the Stuart Highway, or heading over to Eyre Peninsula.

What they're talking about are turnout lanes which are a lane beside the road with no median/barrier and you're expected to slow down or maybe stop very briefly, purely to let faster traffic through. There are some up on the road past Pichi Richi Park to Quorn if you ever drive through the Southern Flinders, but they're not overly common in SA.

I've seen them formally in northern USA (Idaho going into Washington state, maybe) where they are risky and unclear, and I've seen informal ones on roads east of the Sierra Nevada which are like your quote - rough, unpredictable poorly laid asphalt or gravel.