He died at the scene from a severe head injury, while the other driver survived.
In his recommendations, Coroner Robb said it should be mandatory for doctors to report unfit drivers to the New Zealand Transport Authority (NZTA) under what would be a Land Transport Act amendment.
While not legally complied to, no medical professionals informed police or the NZTA that Gillanders-Ryan's driver's licence should be cancelled and first allowed him to voluntarily surrender his licence.
Currently doctors only have to report an unfit driver to the NZTA if they believe the patient will continue to drive.
Gillanders-Ryan was upset at no longer being able to drive and ignored his medical advice.
He told a psychiatric nurse he had been "robbed of his independence and his rights".
His wife of 52 years, Beverly Gillanders-Ryan, also tried to hide his car keys to stop him getting behind the wheel and even removed a fuse from his ute to disable the vehicle.
Tragically, Gillanders-Ryan and his wife had already lost two sons in separate motorbike accidents.
As a result of the crash, the Lakes District Health Board has already changed its practice of allowing people to voluntarily surrendering their licence.
Now the DHB informs the NZTA of unfit drivers.
But in a letter to Coroner Robb other doctors around the country said they will not follow the DHB's lead and will continue to follow current guidance - raising concerns about the doctor-patient relationship.
The Royal New Zealand College of General Practitioners also told the coroner they are "very conscious that telling a patient that they are unfit to drive can have a negative impact on the doctor-patient relationship".
"This can be further exacerbated when the doctor then reports the patient as unfit to drive to the NZTA."
The doctors said should reporting to the NZTA become mandatory then they "would expect that the resources provided to GPs would also need to be updated".
"Until such time as the NZTA advice is updated, GPs will continue to follow current guidance."
Coroner Robb said the removal of the ability to drive is a significant loss of independence and may be the subject of unkept promises but the approach now taken by Lakes DHB is a "pragmatic" one.
He said it triggers the NZTA to take steps to prevent the responsibility resting solely on family members to stop unfit drivers.
The Ministry of Transport and the NZTA also replied to Coroner Robb's recommendations in a letter and said a law change could "potentially have a beneficial impact on road safety" and "reduce the burden on family".
An amendment will be investigated as part of the ministry's review of the transport regulatory regime next year.