Hopefully your family is never nailed by an 90 year old guy with recent vision changes,a history of “TIAs” (those are “mini strokes”) while driving,at night,in a place unfamiliar to him.
But how is that different than a 33 year old guy who just wasn’t paying attention? Again Van Dyke was driving in bad weather and there were probably plenty of people in the area far younger than him that also hit a bad patch of road and got in accidents. Your assumption about age is just silly. Sure some people get old and lose the skills. Some don’t. There’s a lot of genetic and lifestyle lottery in how we age and what skills we maintain and lose over the course of it. To blanket say “90 year olds can’t drive” is, as I already said DUMB.