It breaks your heart when these things happen, especially when we know it is so easily prevented.
When my new neighbors built their house, I was out mowing with the 5' rear PTO Grooming mower. I stopped to talk to the Grandfather (his son and daughter-in-law's house). He had his two grandsons with him and, ofcourse, they asked if they could ride on the tractor. Before I could answer, Grandpa chimed in that they ride on their uncle's tractor all the time. I explained, as diplomatically as I could, the danger of the practice, emphasizing that I couldn't live with myself if I let them ride and some thing happened to them. It didn't seem to get through to Grandpa and, ofcourse, not the kids. He just scowled as if I were either some kind of jerk or that I was way too overcautious. Now when I see the kids when I'm out on the tractor, they just scowl (wonder where they learned that) and turn the other way. Oh well, I'd rather they think I'm a jerk than for them to get shredded.
BTW; Grandpa was volunteer fire for years and a local EMT...go figure! Also, he is frequently out with his chainsaw in sneakers, with no gloves, ear protection, helmet, and certainly no chaps. And, now their lawn is in, I frequently see the kids getting a ride on the riding lawn mower on some fairly steep terrain. I hope some angel is watching over them.
Tom