There is a big difference between 5 and 50 years driving. Your insurance has stats to back this up and will give lower premiums.
Now skills decline at 70 so that may offset some of it.
Now skills decline at 70 so that may offset some of it.
The implication isn't that drivers get steadily better as they age but that the longer your history of safe driving, the less likely you are to become a liability.
Lower premiums might just be because they've been in less accidents for that long, so they've sustained consistent level of safe driving and it doesn't translate to the idea that they necessarily are more skilled drivers.
Doing a task consistently is what insurance companies are rewarding, but that doesn't necessarily mean that they're more skilled at it, they've just been at it longer.
Not so much with driving ability, but very often a proportional gap in recognizing and handling vehicle problems, especially situations that don't come up very often.
The average person at 66 is much more risk averse than they were at 21.