Sure, but that fails to consider the context and the broader point of living. The point of living isn't to maximize safety at all costs and sacrifice everything else at its altar. The context is that declining birth rates are a major problem, so if it were the case that car seats dramatically affect birth rates, this is an important thing to consider. The bit about letting children die and mourning is an empty appeal to emotion that I will justifiably ignore.
> As with many relaxed regulations, I suspect that it will result in disparate negative impact to poor people.
And you didn't specify why. Why would this negatively impact the poor? Blanket statements that appeal to emotionally charged subjects like the poor are don't contribute any substance. The author points to the cost of car seats. They're not cheap. Having to buy them certainly affects the poor. Now you have less money for your kids, or you're being coerced into having less than the rich because you cannot afford a larger car.
> Build public transit that is both safer for all involved and also allows any number of familial transit configurations.
I agree that there is underinvestment in public transportation in the US, but once again, you'll handwaving and speaking from a position that's disconnected from reality as it is. The US isn't going to suddenly build up a huge base of public infrastructure. The urban planning and "rhythms of life" dosn't even accommodate this possibility easily. And even in Europe, where public transportation is much better, people living in rural or suburban areas don't necessarily have great access to public transportation. Furthermore, have you tried shuffling a bunch of kids around by public transportation? You want to carry all the stuff they might need? Even people in cities find cars a huge help in those cases.
If car seat laws are indeed a major contributing factor to plummeting birth rates, then it makes sense to consider repealing them, especially if car seats don't provide any real safety[0]. Or if we can change car seat belts to accommodate the very young in a way that doesn't require car seats (and where more children can be fitted in the back seat), that, too, would be great.
[0] https://abcnews.go.com/GMA/Parenting/child-safety-car-seats/...