While I understand what you're saying, I have some things to add:
1. Cape Town and Lagos (Nigeria in General) have virtually nothing in common. Cape Town is essentially Zürich compared to Nigerian cities.
2. state run institutions, like health, education, police, water, sanitation, conservation and everything else people take for granted in well run countries, you find a dramatic decline. ... a widening gap between rich and poor, civil unrest, growth in private healthcare and security, unreliable and expensive power supply and high crime rate, often violent.
You have just described the exact challenges faced by the United States.
3. There are millions of stories about how bleak "Africa" is and how many challenges it faces. I have been constantly shocked by how developed many places are, and how fast they are not only catching up to, but in some cases surpassing "Developed" places. For example: have you been to Brazzaville? very nice and modern city, fantastic roads all over the Rep. Congo now - Pointe Noire too. Lomé in Togo is another great example.
4. In my experience Africans are positive and optimistic about the future. That means they're working hard to make stuff better, as apposed to those who sit around in the developed world and complain about how everything is getting worse. I wonder where we'll be in ~20 more years.