Interesting the number of posters who decry the lawsuit prone USA. Like UK and most Western countries the USA has a "Duty of Care" and pretty well at the top is the duty of care to paying clients on your property. That duty extends to "foreseeable" incidents and way up in that list is incidents that have happened to clients before that the vendor knew or should have known about.
i.e. Other people have been killed or maimed by walking into helicopter tail rotors. The vendor knew about such incidents and therefore should have taken all precautions against it happening. Since we don't know about the precautions in this accident, we don't even know fully what actually happened it is rather speculative to comment. (I know, that's what this forum does, not a criticism.)
This is not a comment on this accident. Different country, different circumstances, maybe. Just commenting on attitude.