Terrible day at my Son's workplace

Who wears a harness when working on a ladder?

Sorry about your son. Seeing this stuff is traumatic. I saw a guy fall from a roof when he lost grip. He turned out to be okay but injuries have the effect of making others suddenly feel vulnerable. THAT can lead to making mistakes that one might not make.
You hear of Police that are forced to second guess their actions after a recent incident. This can happen in other segments of society too.
Safety is more of a state of mind than a tangible thing. I'd rather rely on my own wits than an harness, a barrier or anything else. A person with good common sense may never incur an injury while an idiot in a plastic bubble may still get hurt daily.
Its OSHA rules now days to wear a harness and safety hook when working over 5 feet off the ground in factory's, the poor guy had his harness on per rules but hadn't reattached it.