There is often a catalogue of failings behind a fatal electrical incident. In this case the human angle on the case is thrown into stark relief as a young life was lost due to the errors knowingly committed by people with a duty of care. Without wishing in any way to diminish the importance of that, it's interesting to note how far we have come in managing the risks associated with technical hazards. Despite all the electrical equipment in use, millions of appliances, millions of circuits, live 24/7, when something goes wrong badly enough to kill, it can make national press.
I think it's important to use insights like this to home-in on the problem areas. The lad was not shocked by a circuit where the Zs was too high due to failure to compensate for the conductors being warmer during operation than testing. He was shocked because the whole premises' MET was floating free perhaps for a decade. The fine technical details are important, but equally or more important are the basic provisions for safety and doing business in such a way as to root out installations that do not meet them and get them sorted.
We sometimes hear about installations that seem likely to cause harm (e.g. with C1's or borderline C1's) and the only practical advice that can be given is to walk away. Those are the installations where one really needs to double down and find a solution for the customer to get the worst of the risks under control, even at the expense of not working to one's own normal standards of perfection. It's not easy.