Without naming which relative it is, I have one who, after an accident and a medical condition which legally forced her doctor to indicate to the state that she needed a re-test, had her license revoked. Her vision was fine, but her moderate dementia prevented her from passing part of the driver’s test. Mad does not start to describe her sentiments, but it is better than getting somebody killed.
In her case, though, the family had to put one of those anti-theft clubs on the car to keep her from driving it…she had keys to her vehicle hidden all over the place. Her memory got so bad that she didn’t remember that her license had been revoked, let alone why!
Age alone does not indicate whether a person is capable of driving. These things that may decline due to age-related medical decline do: eyesight, reflexes, reasoning ability, skill at risk assessment and the ability to pay attention to detail and multiple simulataneous stimuli. (Making it obvious why some people under 25 are also unfit to drive.)
The answer to the OPs question, though, depends on the circumstances surrounding those accidents. He might check with his state DMV to see if they have a policy that allows anonymous tips on drivers who might pose a hazard, but should also realize that revoking the license may not solve the problem. It also may cause problems, such as whether the man can own a car in his state when he can’t get insurance because he has no license. Convincing an older person, particularly a man over 65, to give up the keys is one thing. Getting him to give up the title to his car is a horse of a different color.
If the driving can be stopped without revoking the license, so much the better.
Also, some insurance companies will give older drivers a price break if they attend safety seminars such as “Fifty-five Alive.” My MIL went to one of these, and decided on her own to give up driving after dark and when road conditions might be hazardous. She plans her outings to avoid heavy traffic conditions, too. That is the best of both worlds.