When you looked out of the windows of the classroom I used to teach in, all you could see was a steep grass bank in front of you. The council staff used to cut the grass on that bank by standing at the top and pulling a hover mower up and down it with a rope. I frequently thought that one day one of the guys would slip downwards, just as his hover mower was coming upwards. I certainly wasn't alone in spotting the risk, as numerous kids commented on it, but the practice continued for year after year regardless.
Then finally one day my colleague, just a little way along the corridor from me, had her lesson interrupted by a council worker banging on her classroom window and asking her to call an ambulance because the inevitable had finally happened. If dozens of kids could see the risk, why couldn't the council staff (or their bosses), I wonder?