Why do Mama and Papa Logan, as well as Uncle Hammer and Big Ma, not do more to shield the children from these serious situations and harsh realities?

The adults in the novel believe it is necessary for the children to understand the reality of their world. They don't necessarily want to frighten them, but they also want to try and prevent them from making mistakes. The Logan's world is harsh and difficult, but it's also a world filled with love, support, and family.