Every witness has a different point of view and so the truth of what happened is mixed in all their stories. The only person who knows what happened is the driver and I'm sure his stories is a bias one.

 

A policeman’s headache begins when there are more than one witness.

For every witness there is a different point of view.
Just as has been demonstrated here, we have all read the same articles and police reports, we all read the exact same words. Yet many various interpretations have been expressed of those exact same words.

It is common sense to give on site witnesses more creditability. It doesn’t take a degree in psychology to know that if you ask someone right after it happened, they give you one story, asks that same person later and there are always variations. Sometimes it's something else they remember; sometimes it's something that they think they saw. Which makes it less reliable in turn reducing credibility of their later recollection.
If the subject has slept, it is commmon knowledge that more facts have been lost and more imagination has been input.