…you can make a 99.99% safe highway?
You could make all roads 99.9% safe for free (well, for those cost of a little legislation). Institute a 25mph/40kph maximum speed limit. You just saved 40,000 lives in the US alone! And herein lies the real problem and what dragonchild is talking about. For those 40,000 lives you will pay uncountable billions, eventually trillions, in lost time, work hours, unused infrastructure, higher gasoline consumption, more pollution, fewer jobs, less agriculture, etc, etc. Everyone will suffer -- not just the unlucky, or the unseatbelted, drunk, or over-tired who got what they asked for -- quite a bit in this particular case, and it seems likely that more people would die in the long run from the staggering losses to mobility and the economy than would ever die in car wrecks.