I am far from a helicopter mom and do encourage my kids to solve their own problems when they are able, but learning to work things out and be kind is a skill that kids need to be taught. It takes years. It is not something that they are born knowing how to do or can learn how to do by the time they are 5. They need to be shown how to walk through the situation again, but this time, respond the right way. That requires a watchful and involved parent. And if you don't intervene, you (collective you) might be unaware if one child is bullying the other. The victim needs to learn to stand up for him or herself and the bully needs to learn to be kind and have self control. But if mom always tells the kids to go work things out on their own, they won't learn how to do this.