It cites that investigation branches exist for accidents involving air, rail, and water in the UK, but none exists for UK roads. This despite the total over an 11-year period is 504 for air, rail and water, yet 36,781 for UK roads.
It goes on to say that the police priorities are based on finding out who is to blame, rather than investigating the cause. This is not surprising, because that is what the police are for; to uphold the law, which means bringing charges where appropriate.
The police do investigate up to a point, but their resources do not provide for, or allow, extended investigation beyond satisfying themselves regarding the legal position of those involved in the accident.
I fully agree that some investigative body, specifically tasked to use the information to reduce/prevent accidents, certainly seems necessary. But, if you consider the situation in detail, the logistics are truly formidable.
For air, rail and sea, the operating regimes are more strictly controlled, the areas of operation are confined to known corridors, the operating vehicles and personnel are constantly tracked, and the number of vehicles comparitively small.
By comparison, in a road crash, contributary vehicles may not actually collide, and simply vanish from the scene unrecorded. At the scene itself, events leading up to a road crash can be due to a wide range of causes, and any witness evidence will very often be either biased towards self-defence by those involved, or unreliable opinions by witnesses, who may well have noticed nothing leading up to the crash; and only having a state of awareness after the crash.
Add to this the frightening number of illegal drivers, who do not even consider normal traffic behavioural requirements, and the drivers who have knowingly broken a rule but simply lie about it, and the establishment of useful facts are significantly difficult to assemble.
This is why I personally believe such a body is unlikely to come into being.