Furthermore, I assume that many cars on the roads today don't have the most modern air bag systems and passive features that increase survivability in a crash. To say nothing of the fact that they're simply old which certainly isn't likely to help with their likelihood to get in a crash or survive one.

I expect that if every car in the US were replaced with a new one with most of the available modern safety features, you'd reduce the current fatality rate by a very significant percentage.

One of my vehicles is quite old. But I'm not going to replace it just to get new safety features.