Parents are spending like 2X of their time on their children now than they did decades ago, so your overall thesis is exactly backwards. Parenting is perceived

Parents are spending like 2X of their time on their children now than they did decades ago, so your overall thesis is exactly backwards. Parenting is perceived as a much more intensive activity now, which is so many people are having fewer (or no) kids. The reason seems to be safety culture: Despite society actually being much safer than it was back then, parents don't perceive this to be true, thus children aren't allowed out to play on their own like they used to be. It used to be common that children would be out all day every day planning amongst their own, and only came back for dinner and then bedtime curfew. And that included getting themselves to and from school when school was in session.