It's not an arms race. Once the cars are loud enough to hear on a quiet street, nobody needs them to get any louder. The problem is that everyone on the planet has grown up in an environment in which relative quiet means no car is coming. It doesn't matter one bit if the car sounds are drowned out. Nobody steps out into the street without looking just because it's really noisy and they can't tell if a car's coming or not. People used to do that, but they're all dead now.
Tire noise is not always audible, certainly not above a light wind if the street is dry. Everyone who lives in the suburbs and goes for a walk occasionally knows this. Electric cars can make useful noises without being anywhere near as noisy as gas-powered cars.
The issue here is not requiring everything that might hurt you to carry a warning. The issue is whether or not it's okay to have things that have carried warnings for the entire lifetime of everyone now living to suddenly stop doing so. It's not.
Bicycle riders can indeed hurt you, but (a) they tend to be less fatal than cars when they strike pedestrians; (b) bicyclists are aware of the fact that they're inaudible (in fact, many have bells or horns); and (c) nobody on this planet has grown up in an environment in which bicycles always make loud noises. Should we be worried about defective noise makers on cars? Probably not if they're as rare as defective steering, defective drivers, etc.