I like the US way, call me parochial.
".......The purpose is not to assign fault........."
I don't think anyone here disputes that, per se: I think we all deplore the fact that in France it is necessary to hold a criminal trial to assign responsibility for damages and compensation, and that the threat of such a trial has a chilling effect on impartial accident investigation. We all wish that France had an inquest system.
But what is inescapable is that the accident happened in France, and as a consequence the investigation and subsequent actions are within and subject to French legal jurisdiction. Opinions ventured from the point of view of other legal jurisdictions
are entirely irrelevant.
Edit: I should add, that includes opinions from a UK legal perspective. We have inquests and Coroner's Courts here. They're useful.