If I had to make a guess, a big part of this is that sub-Sahara Africa has a lot of tropical diseases and a generally more challenging environment, health-wise.
While North Africa is really operating under mostly the same environmental circumstances as Europe, but less wealth and water.
Of course, government competence and general country wealth do certainly come into play as well and most countries in Africa aren't so far known for good governance. So it probably is a mix of environment and policies. But you may want to compare to other tropical locations with similar wealth and disease burdens.
Estimates for malaria elimination alone range at 6 yrs (old paper)
Looking at your map, "Southern-end of Africa" countries, which are more temperate in climate, show a fair bit of green and aren't that far off say India. And that's not only limited to South Africa which is the most developed country in the area.