I agree, especially since medical tests won’t show the driver slowing down as they enter a roundabout or taking a full minute to shift lanes or positioning themselves so they can’t even look in the rearview mirror.

A ton of driving is about behaviors and tendencies. A driver that has no awareness of other drivers is a dangerous driver, regardless of how good their heart, eyes, or reaction time. Dementia obviously affects this, but you can get a clean bill of health from your doctor and then drive off home in the left lane at 5 below the speed limit because other people are just going too damn fast.