"Incompetence and dereliction of duty" are cop-outs, in the case that there are underlying causes.

If, say, reduced staffing and increasing demand leads to worsened worker conditions, and that in turn affects their ability to do their work, or impairs their judgment, then it's crucial to uncover those issues.

I'm sure the shipping companies etc. would love to run with the explanation that the workers caused this by being stupid, and nothing else, though.