Eyewitness evidence is turning out to be some of the most unreliable evidence out there.
It is not the "fault" of honest people, rather it is the fault of our brain, and how the brain attempts to piece together events to create a timeline, a story.
First time I read about the "Invisible Gorilla on the Basketball court" I was very surprised about the number of people who did not see the Gorilla. Glad I was not part of the experiment or I would have felt very foolish if I missed the Gorilla.
This New York article discusses this.
This article shows that 70 percent of Chicago accident reports are incomplete and 30 percent grossly wrong.
In my opinion, the greatest reason for this is that report filling is boring work and the Cop does not have "skin in the game" about the accuracy of the final product.