Harnesses are unheard off in many parts of the world, guess it comes down to bravado mostly. When I worked in Algeria there were loads of stupid deaths, usually falling from the derrick of the oil rig.
The worst one I saw photos of was a guy who'd been wearing a harness but had it trailing behind him as he was working on the rig floor. It got caught up in spinning machinery and he was pulled in to it and ripped to pieces. Nasty pictures