Another way of looking at it is that it is likely much easier for "Fate" to turn a minor accident into a serious one than it is to turn a serious one into a minor one. simply because minor accidents out weigh serious ones by such a large factor.
Reduce the minor accidents and you will also reduce the serious ones.
In any case I have always felt that "Fatals" are over investigated compared to other accidents simply because they involve fatalities.
Consider the accident a while back where a recovery vehicle ran into the back of a lorry, Had "exactly" the same incident occured but with no fatalities, would there have been anything like as much investication??
If garry hart had had "exactly" the same accident but where there wasn't a railway line and he just came to rest in a field. Would he even have been prosecuted??
I suspect not.
Whether or not somebody dies in a RTA is largely down to luck. Its "accidents" we need to be investigating, not "Fatals" as such
The other problem with accedent investigation is that i suspect they are skewed by political pressure and box ticking.
EG Some years ago I read of an accident involving a collision on a contraflow. An Unlicenced minicab lost controll, ploughed through the cones and collided with a vhicle traveling in the opposite direction.
However, the "Victim" was found to be over the limit So Guess who lost his licence. And I will bet a crate of bubbly that this was listed in the official statistics as a "Drink related accident"