Accretion of power through violence, i think. Europe has laws, “order” and generally is peaceful, while African countries are often governed by who ever has the most efficient use of violence to be in power. These people of course, dont care about those around them and only want more for themselves which contributes to the general population having less chances for a good life because there’s no safety to thrive in.
Another issue is i think, Europe has a varied biodome that can support many things to grow. Africa, in the largest part, is dirt and desert where only specific things grow, most of which arent the best for export or trade. Those that are, again, are probably controlled by warlords and other scum.