The devastated families of three people killed in a crash involving a learner driver have been left furious after a coroner exposed a licence system devoid of safeguards.

A South Australian coroner has called for a licensing overhaul after a 2020 tragedy that unfolded when a teenage learner driver with medical conditions "zoned out".

Naomi Kereru recommended young people visit a GP for clearance before applying for a learner's permit following the deaths of Ian (Ned) Walker, 80, Nan Walker, 70, and their daughter Sue Skeer, 55.

The trio were killed when their vehicle was involved in a head-on collision at Suttontown, in SA's southeast, in November 2020.

The other car was driven by a 16-year-old boy, known as TB, who has autism, ADHD and Tourette syndrome.

None of the conditions were reported on the medical and impairments section on his learner's permit application.

He was later found guilty of careless driving but not guilty of the more serious crime of causing death by dangerous driving.

A medical assessment after the crash found TB did not meet the medical standard for driving because he was "easily bored and loses focus", telling police he "zoned out" before the crash.

"The fact that one person's momentary health episode can so easily claim the lives of three other people demonstrates the value in a health certificate step being added to the licence qualification process," Ms Kereru said in findings released on Thursday.

"The Skeers and Walkers lost a large part of their family in an instant, in what must feel like a cruel affair."

In a statement, the families said the findings "laid bare a truth that is as devastating as it is infuriating".

The findings revealed a licensing framework "completely devoid of institutional safeguards, checks or balances" and inexplicably relied entirely on unverified self-reporting, they said.

"Reading the details of how a combination of severe, diagnosed neurological conditions was simply allowed to go unchecked has reopened our wounds, leaving us with an overwhelming sense of disappointment and sorrow," the families said.

"While no outcome can ever repair our family or fill the immense void left by the loss of Nan, Ian, and Suzanne, we demand that their significance be reflected in immediate, meaningful legislative change."

Ms Kereru found TB's conditions should have been disclosed on the learner's permit form.

"The attention-deficit component of the ADHD diagnosis alone had the capacity to affect driving, where constant attention is a key requirement," she said.

The inquest had highlighted a flaw in the system of self-reporting that created increased risk to all road users, she said.

It was unfortunate that TB and his mother were left to be the conclusive decision-makers on whether his complex health conditions would have any effect on his driving, the coroner added.

"It was, more likely than not, decided not to disclose the conditions because doing so would have made the process more difficult," she said.

TB's mum was trying to be a good mother and placed reliance on her own faith in her son instead of allowing independent advice to decide whether he ought to be driving or not, Ms Kereru added.

A young person's yearning to get their driver's licence "does not sit well" with a self-reporting regime, the coroner said.

"There are no safeguards in place to counteract the temptation not to declare a medical condition when making an application for the first issue of a learner's permit," she said.

Requiring a medical certificate to obtain a learners permit would make every road user safer in the knowledge that each person's fitness to drive was assessed by a doctor at the outset of their driving career, the coroner found.

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