That was an extreme example,the point is that kids can end up in the water in unexpected ways. Even parents that would never intentionally leave children in the water alone can end up in a situation where a child is unattended in the water. Perhaps a better example is when you have 4 kids to keep an eye on at a public pool, and you lose track of one while dealing with an injury to another, or reapplying sunscreen, or a number of other reasons to be distracted. Or what about the situation where you send your kids outside to play and they sneak back to the pool? No sensible person would let their children into the pool alone, but it can absolutely happen to even the most careful adult.