I am curious as to why the police have dropped the word accident?
As Scotty said, they don't want to imply they are genuine accidents as most are not.
I was at a talk a few weeks ago with a very experienced police officer who is now a car & bike examiner. He called them "mistakes".
For the record I fully accept that if a deer jumps out right in front of you then you probably can't avoid it and some are unavoidable random occurences.

And how do the police know that “most accidents are avoidable”?
They can measure all sorts of things speed, tyre tread, braking distance (from skid marks), blood alchohol level etc.

As an example if someone had bald tyres, but sufficient distance to stop with legal tyres, then the conclusion is obvious.
Similarly if someone lost control with no other negative factors but was 5 times over the blood alchohol limit, then conclusions can be drawn about the cause.

I would never be so bold as to say most accidents are avoidable.
You and I shouldn't make those claim I agree. I think the police are in a good position to though.

but it is very easy for the police and other orgoniseations to look back after the event and suggest that the accident was avoidable.
Yes they have decades of experience and statistics on their side.
Many accidents involve drugs, drink, illegal tyres, no seat belts. Those that fall into that category are definitely not random unavoidable occurences.
Remember a criminal conviction has to be proved "beyond reasonable doubt" so the police don't just make stuff up for fun, they have very strict criteria certainly at the crinimal level.
A deer jumping out in front of you is a random unavoidable occurence, but poor tyres, lack of braking distance too much alchohol, too much speed are not.

You can personally increase your odds by getting more training. There are some stats to show this and you can get discounts for insurers (and they wouldn't give you money back if they didn't think it as true).