This is comparable, though less than, the number of people struck by lightning each year in the UK (30-60). I don't see parents berating one another over their strategies to make their children safe from this phenomenon.
larry while I don't disagree with you (that people have an absurdly inconsistent attitude to risk), some of your lines of argument are daft. Response to risk should be governed not only by the probability of an outcome, but by the cost of mitigating it. To choose to buy one car seat over another, and spend £100-£200 more, is for many parents a reasonable proposition (I recognise that the cost will not be felt equally for all, and for some it is intolerable). Additionally, a parent putting a child in a car is ultimately choosing to take an avoidable risk, and as part of that decision, may pay extra attention to minimising it.
The example of being hit by lightning is unfair: first, because it is quite likely that we already take the equivalent (low cost) precaution that advocates of ERF car seats argue for - we don't go out in storms and stand next to telephone poles. Second, because mitigating the risk entirely might mean never leaving the house. So a fairer comparison would be if people on this thread were saying, car accidents are so terrible, you must never put your child in a car.
It is much more successful to argue that the benefit of ERF (injury sustained in a given accident) is minimal and doesn't justify the cost. But as a pp said, the parents of children who die in RTAs might disagree. 15% doesn't capture the non linear nature of increments of serious injury. Injured, badly injured, very badly injured, dead. In fact, it's binary. Dead, or alive. If DD died in a car accident, I would always regret scrimping on her car seat. If she were struck by lightning, barring obvious risk taking behaviour, I would have little to regret, other than a lack of perfect foresight.