I almost get hit by hybrids when not paying attention. Cars need to make noise like natural gas needs to have a scent added. Safety.
No, seriously, I think you do the blind a disservice. I don't think that blind people rely on, "Hey, did I hear something" to mean, "I can blithely cross the street without danger."
Cars are smaller than trains.
We have to do everything in our power to make sure cars don't have "ringtones".