Problem is that they've been made so dysfunctional by colonialism, and then often even after formally gaining independence, they continued to be purposefully destroyed by colonial forces through colonial taxes, financing corruptions, political influences, etc. Haiti was one of the riches countries in that part of the world, until France killed their economy by sanctions in revenge for their successful slave uprising. It lasted until 20th century, Haiti was paying France huge money. Some African countries are still to this day paying France taxes and France keeps all their money in the French central bank. Other countries like Belguim, Spain and even US were not much better. US dealers were buying off the colonial debts and traded with them on US stock-exchanges until 1940s or so.

And today this continues in the form of corruption by multi-national corporations. Almost all diamond mines are owned by a few western companies. Do you really think they want progressive democratic government in any of those countries? Nope, corrupted dictators are way better for business...