In Ruin, there is a constant threat from this— power given to people who have no status.
The world is in anarchy, but there is a structure to it. Children of experiments (the humans who had once been in the Labs) automatically have more power (even if they don’t have a power), especially once they become a member of their parent’s tribe.
It’s mentioned by a few characters that the younger tribe members have more to prove than the established members. They can fight, or are at least not unfamiliar with fighting. But within the tribe, they often have no status because they are unproven.
So when they run across someone seen as even lesser than themselves (like a stray human or two roaming the Wildlands), it is very likely that they will take the permission to fight and to hurt people to an extreme.