This actually varies a lot depending on the area you are talking about. Some countries have great infrastructure even outside of cities. Others however are lacking a lot of infrastructure. A lot of this can be traced back to how colonizing nations were running their colonies, and then how the US/USSR were using infrastructure aid to help their warlords conduct their operations in the different African countries and then now how China, Russia and the EU is investing in infrastructure that favors their interests. All this foreign efforts are quite disruptive for the local infrasturcture construction. But again it varies a lot between the different countries and you can not say much general about the entire continent as a whole.