The problem with saying 'it was an accident' is that Western society does not allow for an 'accident', especially when financial compensation is an issue.
All accidents are preventable, and what we now do is trace events back to last thing that could have been done differently in order to prevent the accident, and that's where we place 'blame'.
Kid slips on ice in the playground and bumps his head - accident. However, what we do is allocate blame: the teachers, for letting him play there; the caretaker, for not gritting it; the council, for not closing the school; the kid's parents for putting him in inappropriate footwear.
Same thing with Concorde. A mechanic using unauthorised materials; an ill-designed fuel tank system that was vulnerable to impact from below; a tyre-pressure problem that had been known about for years, and had been only partially addressed by the aviation authorities.
There's financial compensation at stake, and so they have to allocate blame to someone so the bill can be paid.