Hunters, as humans, do have the choice to unload their gun before they set it against a tree. They do have the choice to never fire until they see a clear target. They can decide to hunt or fall asleep, but not do both. Hunters can be doggedly stubborn about so many things. Fortunately, safety is one of them.
Most hunters are very good about being safe.
We never read about these hunters. It's why we don't read about more accidents. It should be safe. We forget to check the safety. We're pretty sure we're not falling asleep.