Trauma to the brain stem is more dangerous than trauma to the frontal lobes because the brain stem controls vital functions like breathing, heart rate, and blood pressure, and serves as a bridge between the brain and spinal cord. Any injury to the brain stem can disrupt these functions and lead to life-threatening complications like respiratory failure, cardiac arrest, or hemorrhage. In contrast, the frontal lobes are responsible for cognitive and behavioral functions and while damage to this area can lead to personality changes, it doesn't pose an immediate threat to survival. In summary, injury to the brain stem can be deadly due to its critical role in controlling basic life-sustaining functions.