Remember kids... always wear a helmet. (The almighty bikeradar helmet thread)

The nature of the trials is my point. They are 'unblindable' therefore they can never meet the gold standard set up by John Cochrane when he established the review system.
Most of the criticism of the early trials relates to their failure to remove bias, or successfully randomise the cases. The 2005 edition of the review is a re-edit of the 2000 version after they removed the fictional quotes attributed to Mayer Hillman.
The main reason why the predictions from these 20 year old trials keep being repeated is not that they are the best science but they claim the biggest benefit and so are beloved by the helmet promoters and the press.

If you think that the Cochrane people are a sinister shadowy cabal, you're w r o n g.