I can partly explain why.
Every year, in the summertime there is a peak here of riders, for obvious reasons (summertime of course).
And with the peak of riders, the peak of accidents also peak.
In short, in the months May-June happen the most accidents with motorcyclists.
The peak is there because many riders do not ride outside summertime, its easy to conclude that an all year rider is more skilled than somebody who only rides a few months a year.
You simply cannot argue or even deny this fact.
That said, the government offers free riding lessons every summer.
Every motorcyclist can sign up for it thru a website and best of all, its free!
The lessons are being given by the police themselves.
Every year in summer we see this in the news and they show images and interview some of the trainees and the police.
In short, the images, the trainees are almost all of them "elderly" guys
Dunno how it is in America, but in Belgium (I suspect also in Europe), there was a time when they used to hand over licenses to whomever wanted one.
Talking about the early fifties, sixties, seventies.
I could be a decade wrong, but you have to forgive me for not being accurate since for me, thats a time long gone

But not so long ago, people that have a car license from a certain date (pré 19.. dunno for sure), could automatically ride a motorcycle. PERIOD

There was no limit to wich kind of motorcycle, there were no restrictions in power, weight, power to weight ratio, nothing, nada...if you had a car license, you could buy any motorcycle, an Electra Glide, a Goldwing, a sportsbike (okay, in those days they weren't as crazy fast as now), whatever, it didnt matter, you just could buy and ride off
Absolute freedom huh
I think don't have to explain that exactly that generation of riders today, aren't as skilled riders when compared to the youngster who pay a lot of money to follow motorcycle training in order to obtain your motorcycle license.
I am talking purely about skills, not about common sense...

And the rules today got even more stricter to obtain a motorcycle license since 2014.
I was even the last generation of the previous framework of rules.
Now they are all the same in Europe and ruled by European law.
In a nutshell, more and harder lessons (dunno the details of current rules).
But also, more expensive.
Critiques would say, its just a way to get more money out of our pockets...whatever it may be, the official reason for the stricter lessons and rules is because the number of motorcycle accidents in Europe was too high and they wanted to do something about it.
Back to the "older" riders.
When I see the news and hear the interviews I am surprised some of them seemed to have learned things thats seemed for granted for the rest of us riders that had to take lessons.

Again, they may have less skilled, but that doesnt mean the elder riders have less common sense

Because if skills and techniques are everything, you wouldn find one young motorcycle victim huh, but they too exist.
I hope to find official statistics from European or Belgian institutions regarding the age of riders involved in motorcycle accidents.
If I find something reliable I will post it here.