Maybe they are descended from wolves but never really became dogs?:
Dogs are generally considered the first domesticated animal, while its ancestor is generally considered to be the wolf, but where the Australian dingo fits into this framework is still debated, according to a retired Penn State anthropologist.
“Indigenous Australians understood that there was something different about the dingoes and the colonial dogs,” said Pat Shipman, retired adjunct professor of anthropology, Penn State. “They really are, I think, different animals. They react differently to humans. A lot of genetic and behavioral work has been done with wolves, dogs and dingoes. Dingoes come out somewhere in between.”
Wolves, dogs and dingoes are all species of the canidae family and are called canids. In most animals, hybridization between closely related species does not happen, or like female horses and male donkeys, produce mules — usually non-fertile offspring. However, many canid species, including wolves, dingoes and dogs, can interbreed and produce fertile offspring. Defining species boundaries in canids becomes more difficult.
Domestic dogs came to the Australian continent in 1788 with the first 11 ships of convicts, but dingoes were already there, as were aboriginal Australians who arrived on the continent about 65,000 years ago. A large portion of dingoes in Australia today have domestic dog in their ancestry, but dingoes came to Australia at least 4,000 years ago according to fossil evidence. Shipman believes that date may be even earlier, but no fossils have yet been found. Penn State, “Wolves, dogs and dingoes, oh my” at ScienceDaily
The paper is open access.
Here’s one example of the difference:
While indigenous Australians stole dingo puppies from their dens and raised them, these puppies generally left human homes at maturity and went off to breed and raise offspring. The ability to closely bond with humans is limited in dingoes, although present in dogs. Native Australians also did not manipulate dingo breeding, which is a hallmark of domestication.Penn State, “Wolves, dogs and dingoes, oh my” at ScienceDaily
Dingoes are limited in their ability to eat starchy foods, which dogs learned from living constantly with humans. Their behavior is thought to be midway between wolves and dogs. Apart from that, no one knows much.