About half of women never understand it having or not having children. They don't want to admit it because it's a shame to regret one's own children, but many of them do. Vast majority of men never understand it (mostly because they are married off before they want it, if they married at appropriate age i.e. 45-50, they'd be ok with it, but this is not what women want, they want to take men before they understand they don't want it).

Key is choice. People are not having kids for one stupid simple reason - because they can.

This is why the problem is just the same in every civilisation or culture, it is not at all confined to "Western", "Christian", "Liberal" or "Rich" world. It's everywhere without exception, maybe (hopefully) except Israel. Because Haredim don't give their women a choice.