Why is it dangerous if passengers sitting in the rear do not wear their seatbelts?

In German traffic safety rules, passengers in the rear seats must wear seatbelts because, even at low speeds, not wearing a seatbelt can lead to serious injuries. Unbelted passengers can be thrown forward with great force during a sudden stop or collision, which can injure themselves and also passengers sitting in the front seats. In extreme cases, unbelted rear passengers can be ejected from the vehicle, posing a life-threatening risk. Therefore, wearing seatbelts in the back is crucial to protect everyone inside the car.