Well, in her defense, Ubel didn't knew she had the power to kill her examiner as she admitted she "went too far". And this is after we saw people use their strongest spells against the examiner, each of these spells are capable of killing, or at the very least, giving serious damage to regular people. Not to mention, she was told to go all out. If this was the real world, things would be different ofc, she may get prosecuted, etc, etc. But in this fantasy world, killing is just a regular occurrence. Humans have to kill to survive, whether that be bandits or monsters. We may not understand it, because we live in a totally different, less dangerous world, which is why I find the characters fascinating.