Map Enthusiasts

Why are birth rates so high in these regions and not in more developed areas?

Development is exactly what makes birth rates go down. People also used to have more kids in developed countries in the past, and it went down the more the countries' development indicators went up.

The reason? It's not simple, there are entire theses over the subject and, likely, different causes, but roughly, it's lower education levels, more religious influence, less women rights, criminality, etc. For many people in poorer places, having kids is not an option at all. It "just happens." Actually choosing to have kids is something very recent historically and far from something universal.

might be similar reasons as the american settlers had, more hands for work offsets the extra mouths to feed.

There are a wide variety of reasons that can be explored and discussed but the way you've framed the question suggests such a narrow worldview that one feels it would be a wasted effort.

because "developed nations" are filled with self-indulgent narcissistic selfish people who would understandably spend their resources, all that time and energy, for something more enjoyable than trying to breed some more self-indulgent narcissistic selfish 💩

If you can figure out the answer to this question, you deserve a Nobel prize.

Every country on earth seems to be seeing the same phenomenon: the more developed and comfortable life in your country gets, the more your birthrate tanks. There are lots of theories, but nobody seems to have a good explanation or know what to do about it.

The answer is that those regions are lesser educated and are less likely to know about or use contraceptives. Another is that many of those families hope to obtain cheap child labour in their farms and other itinerary trade. This is why the excessive birth problem is particularly pronounced in the more underdeveloped parts of these countries and not the middle to high class areas.