I think the current safety systems that are beginning to see more adoption (lane drift warning, collision avoidance, automatic braking/engine shut-off, or infra

I think the current safety systems that are beginning to see more adoption (lane drift warning, collision avoidance, automatic braking/engine shut-off, or infrared HUDs etc. in fancier cars) are probably more effective. If the car can detect dangers and act without waiting for you to respond, that's better than just trying to amplify a warning and hoping you hear it and react in time. Now that (in the US) hearing aids are available off the shelf, hopefully we'll soon see more airpod-wannabes that don't look like the traditional aids. Cheaper too. But IMO that's not really a great solution to driving safety. By the time you hear something (be it a horn or a screeching crash) it's usually too late anyway.