Its mostly babysitting. You can divide the effort to raise a child as nursing, teaching and babysitting. The parent is most invested into doing it, but he cannot get very good as a nurse or a teacher (if its not his profession) and babysitting is very low value. You definitely cannot spend 8 hours a day teaching a baby things, and most of the things you teach are quite low skilled (exercise, playing, reading, etc).
If the parent can earn a lot more income by delegating responsibilities he will do it, or rather, most will do it.
If the parent can earn a lot more income by delegating responsibilities he will do it, or rather, most will do it.