What is it about the modern world that makes children act like starving cats all the time? Is it the sugary diets? Is it the overstimulation from media? What the heck changed in the last hundred years or so?
Example, if you let a baby cry at night it will usually stop crying after a few weeks.
Once kids hit ~7 years old it used to be normal to let them wander around the house and neighborhood unsupervised. In most unwesternized countries it still is.
That's how the average family has 6+ kids in some countries. They're only actively caring for a few at a time.
Taking such a relaxed view to parenting in the west would get your kids taken away
aside from that, older kids took care of younger kids, neighborhood groups took care of children together, older relatives who could no longer do hard work supervised the children...
Also some other reasons:
1. Probably there was more general family help with children - grandparents/town/etc was more involved.
2. For kids that were a bit older, they were effectively part of the workforce - apprenticeships, farmhands, etc.
3. Probably, it was more safe to let kids wander around in many cases - cities are particularly complicated, what with streets full of cars and just generally unsafe areas for kids. In a small town, or a family farm, you could let toddlers run around a lot more.
if your work requires focus like writing or programming, then kids are a disruption and you can't do it.
also once factory work was developed, schools for everyone were built too, those developments happened at around the same time.