If car seats significantly decreased the likelihood of serious injury, I would expect that to result in a reduced likelihood of death. E.g. if car seats reduced

If car seats significantly decreased the likelihood of serious injury, I would expect that to result in a reduced likelihood of death. E.g. if car seats reduced the chances of head trauma, that would almost certainly translate into a reduced number of deaths as well. Conversely, I think the fact that we don't see a reduction in the number of deaths is pretty good evidence that car seats also don't significantly reduce the likelihood of serious injury. Perhaps there are certain types of injuries that car seats are more effective than seat belts at preventing - but I would like to see some strong evidence first to justify making car seats mandatory.