I agree with other posters that sound is essential for cars. In the UK, it's not illegal to jaywalk (cross a road at a suitable pause in the traffic when you're not at a pedestrian crossing). In fact, most people in the UK probably don't even know what the word jaywalk means. Without the sound of an approaching car, I can imagine many more accidents. I'm sure all cyclists have stories of missed collisions with pedestrians because pedestrians could not hear an approaching cyclist and assumed the road was clear. With a car, a collision can be fatal.