Why are medical manslaughter cases so rare in Australia?

In 2011, a baby named Tully Oliver Kavanagh died from hypoxic-ischaemic encephalopathy in Adelaide.

Tully was a twin. His mother, against her GP's advice, had opted for a planned homebirth where the only medical supervision was provided by former midwife and homebirth campaigner Lisa Barrett.

Baby Ruby, who would've been Tully's sister, was born first, healthy.

Then the unborn Tully's heart rate dropped and his mother noticed a huge blood clot.

She was rushed to hospital in the family car.

Partway there, the driver pulled over, and Tully was born.

When he arrived unconscious at the Women's and Children's Hospital, clinicians managed to resuscitate him, but diagnosed brain damage that was, in the coroner's words, "incompatible with life".