People like children and family life, most people will want to have a family. the viewpoint that it is/could be morally wrong to have children is very uncommon outside of some western and internet based communities, in fact Im fairly confident the opposite (that having children is morally good) is more common
most people consider their lives worth living, therefore would presumably consider their childrens lives worth living
A few other factors:
in cultures with the highest birthrates, starting a family is often considered the default, and it would be a specific and unusual choice to not do that
Education for women, wealth, and access to birth control are all negatively correlated with birth rates
You mentioned some of these, but I think the strongest take-away here is that you are assuming most people share your viewpoint on several very specific and not-universal moral codes which suggest that people should not only not have children under certain conditions (eg poverty) but also go to great lengths to avoid pregnancy
Primary factor in my opinion:
People like children and family life, most people will want to have a family. the viewpoint that it is/could be morally wrong to have children is very uncommon outside of some western and internet based communities, in fact Im fairly confident the opposite (that having children is morally good) is more common
most people consider their lives worth living, therefore would presumably consider their childrens lives worth living
A few other factors:
in cultures with the highest birthrates, starting a family is often considered the default, and it would be a specific and unusual choice to not do that
Education for women, wealth, and access to birth control are all negatively correlated with birth rates
You mentioned some of these, but I think the strongest take-away here is that you are assuming most people share your viewpoint on several very specific and not-universal moral codes which suggest that people should not only not have children under certain conditions (eg poverty) but also go to great lengths to avoid pregnancy