Totally got my judgeypants on...
Walking round town, I saw a parent help their DS (about 6) climb up onto a high (above waist level) flat-topped railing and held their hand as their DS tip-toed along the top. On the other side of the railing was a drop of about 3m into a river (shallow and slow moving, rocky outcrops).
My heart was in my mouth until the child jumped down. Although the parent was holding the child's hand throughout, I honestly don't think they would have been able to stop them falling if they had slipped.
Was this crazily dangerous or do I just need to get a grip and steel myself for life when my own DS is old enough for climbing and adventure?