Deaf people can't hear cars coming, but that doesn't mean they should have bright flashing lights which are on all the time. Disabled people can't cross the str

Deaf people can't hear cars coming, but that doesn't mean they should have bright flashing lights which are on all the time. Disabled people can't cross the street as fast, but that doesn't mean cars should be limited to 5 mph to ensure they can cross. Aside from the fact that blind people are a small minority of the population (blind meaning people who could not tell visually whether a car was on the road; plenty of people who are legally blind could still make this distinction), there are already other measures in place to prevent cars from hitting blind people. Guide animals are available which can see hybrid cars coming just as well as they can see gasoline-powered cars coming. Signs are posted as warnings in neighborhoods where blind or deaf children are known to live. Furthermore, there are other solutions available. Crossings where this is a concern can have small grooves cut in the road leading up to the crossing so ALL cars make noise when coming through (ever hear a car going over a drawbridge?). It is important to note that crossings where this is a concern are a subset of all crossings and that crossings make up only a small fraction of the surface area of the world's road systems. Maybe 1% of road surface is crossings where blind people need to hear cars coming, but this suggestion would add noise pollution to 100% of road surface traveled by hybrid or electric cars. In your parking lot example, I would add the rule that you should assume every car with a driver in it is running and preparing to move in much the same way that you should assume every gun is loaded and treat it as if it were even if you know it's not. Also, I frequently walk behind cars I know to be running. I am cautious but I am also somewhat relying on the driver seeing me. No amount of safety measures will stop stupid people (like the driver you encountered) from being dangerous. A driver can just as easily gun it going backwards (thus giving people no time to react) in a gasoline car. Finally, there are edge cases where cars making noise makes them more dangerous. Noise draws attention. If you're driving through a particularly bad part of town, you may not want to draw attention. Passing through without making a sound may increase your safety. If you leave your hybrid running (accidentally or intentionally) for a short time, a potential thief might not know it and therefore might not try to steal your car. With a gasoline powered car, they will always know it. The point is that edge cases are just that: edge cases. There is no inherent reason why cars should make noise. None.