I’m not suggesting the following is standard, but the specific sound my car makes allows for people to not just hear the car, but to also know what direction the sound is coming from. The sound is engineered this way.

Compare this with those utility trucks that have those signature “reverse/backing up” (beep…beep…beep) sounds. You can hear it, but it’s almost impossible to tell from what direction. It’s been a complaint by blind people, and there’s still worker incidents where they step into a moving path of a vehicle despite the sound.

You can even make sounds that work against this technique. Home audio systems use directional audio to give the effect of sounds being in certain locations. I wouldn’t want people to be able to change a car sound to something that is more dangerous.