I think older unsure people stick out like sore thumbs when they drive, because they are so slow.
My stepfather will only drive locally now, much to our relief, because when he drove my sister and I back from my grandfather's funeral we hid down low in the back seats on the motorway, we were so embarrassed.
In Lincolnshire the Enemy was old men in flat caps driving painfully slowly and pulling out without looking. A farming friend said that it was because they were all retired tractor drivers, unable to get out of the habit of driving at 10mph and convinced that they had right of way at all times. One neighbour's niece (yes he had been a tractor driver) came round one day to try to get me to write a letter to his GP, saying that I thought that he was 'slightly unsound' and therefore unfit to drive. I refused, and a year later he did cause an accident as he pulled out of his drive without looking. I think the problem really was that the roads are so much busier and people do drive faster. I suspect his victim was speeding through our village and the accident was partly his fault, but there was no denying that Jim did treat the road like a farm track.