You try to explain car accidents deaths away as a necessary evil of sorts. However, I suspect that governments could lower the amount of road related deaths much more cost effectively than deaths through terrorism - as you state, various road safety measures are available, and I’ve no doubt that they could be tightened up for some cost.

Whilst it’s true that everyone benefits from road travel, and therefore that some amount of deaths may be acceptable, it must also be the case that we ought to minimise deaths. Deaths above this minimum cannot be called a necessary evil, precisely because they are not necessary.

Alex