Since all of them are same color its not really color coding and hence not on the legend, its just OPs choice for color of points

click on one

I'm not sure what you're wondering here. Of course physical distance is going to be a dominating factor, but this is measuring packet transit times. The speed of light over half a great-circle is only 67ms or so, ot maybe 100ms considering velocity factor in fiber, so clearly there's more to it than just distance. We can talk about what those other things are, but we both know they exist, right?

Basically yes, as distance is the most important factor when it comes to latency.

I believe it's a combination of a lack of customers and lack of infrastructure. It's a big continent to cover with the necessary fibre capacity, and the market is much smaller for nearby services.

Also what you don't see in things like this, or even a list of datacenter locations, is the relative sizes of the datacenters. After US east/west coasts and Europe, datacenter capacity rapidly tails off. Parts of Asia have plenty but not on the same scale I believe (although I don't know about the Chinese market). The difference in size can be quite a few orders of magnitude between different regions.

Smaller market, less reliable power grids, more challenging heat management, less political stability in many african countries. Also, given their pricing, big cloud vendors AWS are a luxury many local businesses would probably not even consider.

This isn’t just an issue for cloud providers. It’s also not easy to find collocation space either.

My best guess is that it is a combination lower demand (vs rest of world), and infrastructure availability (connectivity + power).

I can imagine a bunch of secondary factors too, but this to me sounds like the key broad reasons.

Azure has Ohio and Texas, but you'll probably not be able to provision all the machines you want so it doesn't really matter.

I think a lot of people are sleeping on the benefits of hosting workloads in these regions. Many finance, banking & insurance companies have already taken advantage. Most of your credit card transactions are handled by data centers that live ~barycentric to the continental US. Much of small US banking tech happens in places like Missouri.

and why are there hardly any in South America and Africa?