Nathaniel and Cheryl David, both 46, were remembered as beautiful members of their church community following the collision with another car on July 10 last year.
The family were driving on the Bass Highway on their way from Launceston to Champagne Falls near Moina in Tasmania's northwest.
Footage of the accident was captured on a camera worn by a police officer who had pulled over another motorist near an overpass, about 40m away from the crash.
It showed the family's Ford on the incorrect side of the highway.
Mr David was driving and Mrs David was in the passenger seat. The pair died almost instantly.
"It is impossible to determine why Mr David drove the vehicle into the wrong lane. Inattention appears to be the most likely explanation," coroner Simon Cooper wrote in findings published on Tuesday.
The couple were pastors at a Victorian church and were weeks away from celebrating their 20th wedding anniversary.
Several members of the public saw the car in the wrong lane before the crash. Two of the couple's children told investigators they also realised the car was in the wrong lane.
"One shouted a warning to his father immediately prior to the crash," Mr Cooper wrote.
The coroner ruled drugs, alcohol, weather, speed and road conditions were not contributing factors to the crash.
The driver of the oncoming car tried to take evasive action. She suffered minor injuries, while her partner was treated for a fractured spine.
Her four-week-old daughter, who was correctly secured in the back seat, escaped unhurt.
Mr Cooper wrote the presence of the police car under the overpass was unlikely to have distracted Mr David, as witnesses saw the car in the wrong lane prior.
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