When must you intervene as bus driver?

Your answer is fully correct. As a bus driver in Germany, you must intervene in all three situations: when passengers improperly use safety devices like emergency door openers, when they throw objects out of the bus, and when they smoke inside the bus. This is because these behaviors compromise safety and the proper operation of the bus. The driver is responsible for maintaining order and safety on board, so intervening helps prevent accidents and ensures compliance with traffic and safety regulations. Remember, as a professional driver, you must always enforce rules that protect passengers and others on the road.