I expect it is like seatbelts on American school buses. The odds that they will help are nearly zero. The odds they may cause harm are also nearly zero. Neither has a clear advantage, but the safety harness has a definite cost to install, to manage, to check to see it's not worn, not been too blasted by UV, that the buckles operate correctly, that they release easily.
I recall the helo flight in NYC where power was lost because something snagged the controls. It landed on the water but only one float deployed. Since it was an open door flight for photography all the passengers had safety harnesses, with the attachment at the back where the passengers could not reach their own; it's not clear to me if it required a special tool or key to prevent passengers from releasing each other. The helo flipped and pulled all the passengers under to drown, unable to escape the harnesses.
The main deaths seem to be from contacting power lines with a distant second being fire.
Apparently sky diving from balloons is dangerous - for the balloon.
https://www.reddit.com/r/SkyDiving/c...nuary_14_2024/
It is just stunning how close this guy was to killing someone on the ground. If one has decided to go it is certainly going to work, but I feel horrible for all the other passengers, the pilot and his crew, and all the people living in the neighborhood who either heard or saw the outcome.
Related:
https://en.wikipedia.org/wiki/List_o...ning_accidents