1 million drivers aged over 80

Age does not make one iota of difference to the quality of driver.
There are brilliant drivers out there who have only recently passed tests and others who have been driving for several decades.
Unfortunately the classic fact is we all tend to think we are better than average drivers, which by definition means over half of us are wrong.
There are a lot of young drivers who think they are so hip and cool rules don't apply and older drivers who assume that they know better due to time behind the wheel, both are wrong.
There is a lot to driving a car, and very little of this is use of the controls.  The biggest things people get wrong are complacency and poor attention.  Being able to push an accelerator pedal is easy, a toddler could do it, knowing if it is safe to with things going on around you is the skill.
I will work from what I see around me to provide some idea of the driving sins I see most commonly and who by.  These are generalisations and not declarations that all in these groups do so.
Poor driving position.  This includes nose to the windscreen and seat leaned so far back the seatbelt is irrelevant and observation is all but impossible.  All ages and genders.  To fix this look at the pros see their seating and posture, copy them.
Hesitancy.  This includes sitting at a junction waiting for no other traffic to be within a mile either way.  Generally older drivers or women.  We all know you need to be sure the road is safe, but if you can't pull out without a light controlled junction please take some lessons.
Speeding, residential.  Youngest and middle aged, predominantly male, but increasingly more female.  Basically there is a rising trend with people who feel the need to recapture their youth by being an idiot and risking lives of children.  If you need speed thrills go to a track, it's fun and has lower fatalities of minors.
Speeding and tailgating general.  Commercial/ reps/ older luxury car owners.  This is stupid on every level we know car brakes have been improved, the human brain and reflexes have not.  Solution think seriously about what you will do if the car in front stops due to a failure, so there would be no brake lights.
Drinking and driving.  Youngest and oldest drivers.  There are masses of us who have lost friends etc. to these morons and still a disproportional amount think they can handle it, even declare they are safer with a few inside them.  If you think you are safer with a drink you are lethal without one, hand in your licence or get some lessons.  Be realistic, no-one can truly handle alcohol and drive, so don't do it.
Use of phone or other distractions when driving.  This includes make up application, shaving, fiddling with sat navs or maps, cigarettes etc.  This is more prevalent in drivers as they get older and more complacent as well as those carrying families.  The proportion also seems to get larger with the price tag of the vehicle, basically a number seem to feel they have paid enough not to have to obey the rules.  If you aren't paying attention to the road around you you are literally a lethal accident waiting to happen.  If there is something you need to do that will take your attention pull over, getting there late is better than not at all or killing another.

Driving is not a right it is a privilege that needs to be earned.  If you think you are without fault, you are likely kidding yourself, if you're more honest, get help either from those you know or professional instructors.
We all age and pick up bad habits in various areas.  The difference between a good old driver and a bad one, is good noticed and remedied, bad assumed perfection due to experience.

As I live in a retirement area (South Devon), there is probably a higher concentration of elderly drivers about. I don't understand the confusion the elderly have with today's traffic. I am 61 so not a boy racer, today an elderly gentleman would not turn right at a GREEN filter but nearly drove through a RED signal at road works. I don't think it is an eyesight problem(unless colour blind) but lack of concentration. As Mike094m remarked, I also ride a scooter, full licence, and the near misses I have on a daily basis from ALL car drivers of all ages is beyond belief. Mostly turning in front or pulling out of roads, garage forecourts. I have my headlight on, plus TWO daylight running lights but I am still invisible. Never mind I hope to be an elderly driver one day, if I survive in the meantime

People are always looking for scapegoats for their own failings. The person who should be banned from driving is YOU!

Allowing for the frailty of old people (and perhaps women?) the risk is far less than 1/3rd.

Old people have to die of something. It is far better to go out with a bang than decline inexorably with debilitation. As to their risk to others - go back to my second line!

The driving test is not at all a test of skill or ability. It is merely a legislative tool that reduces risk merely because of punitive results for speeding etc.

This is the cause of all accidents: if you cannot stop before some one hits you, it is your fault for going too fast. It is foolish to blame others - your laws, protocols rules may mean nothing to some. If you are stationary when the other car hits you, damage will be 1/4 (not 1/2 as momentum is the square of velocity). 1/4 of the force means little or no broken bones/g force enough for death.

 

mazdamike
Colour-blind makes no difference, red is at the top, amber in the middle green at the bottom.  Really not difficult.
Having lived in a few areas, yours included I have noticed that the quality of drivers doesn't change, just the most predominant bad habits.  Because you get used to one set, if you go to another area you are faced with a different set and therefore unprepared.
I have seen people whose driving has seriously deteriorated over time and they have become quite dreadful older drivers.  Others have calmed and settled into driving more confidently and attentively with age, so gone from being dangerous to sensible.
Basically age is not the factor.  The failure in most cars is the loose nut behind the steering wheel, but we are generally too childish to want to hand over control to safer alternatives, technology.  The driver is replaceable, and bit at a time we are being so, in return we will have safer roads.