https://www.reckontalk.com/the-painted-houses-of-the-ndebele...
Of course, do these mansions handle their own services? What do they do about externalities?
Most people will acquire the land in their village. Typically a young couple wanting their own home. There are two options. If you family has some land available, you can just go inform the headman that you will be building your home there. Second option is you approach headman who keeps tabs on land that is available. He will show you were to build. The community is always consulted before land is allocated. For example someone may object that you are too close to them and your livestock might cause problems with his garden. Other objecttions might be that the family closest has a son who is going to build there in near future. The headman tends to be aware of all these maters though and he tends to have spots ready to allocate.
In the past we used to build Blair toilets[0]. People still fetch water from the well. Carrying the bucket on their head or pushing it in wheelbarrow. We are starting to dig boreholes (very expensive) and flushing toilets with septic tanks are starting to appear. Very few though have piped water. Gas stoves also starting to appear along with solar panels for lighting. We still have a long long way to go though.
There is still plenty of tribal lands available. Currently, people tend to settle in the tribal lands that are close to roads and towns. Next step I guess is moving further away from towns. People also have land which they grow crops. This tends to be separate from the homestead and quite substantial in size. A good 100metres by 50/100metres. I see people have started subdividing these fields and settling in them. Fewer people are depending on the harvest now to survive so some of this land is not in use.
I know I haven't answered your question. I really don't know how we are going to transition from the rather informal way in which land is dished out and houses built to the more formal approach. What I do know is it is going to take a long time. Africa currently has other pressing problems. Healthcare, education, corruption ... Whilst there has been the odd controversy here and there land in the tribal areas is not one of the big issues. A lot of it is allocated to families that have lived in the area for generations.
By the time anyone 'official' finds out about your building, it will have been there decades, and usually it will have exceeded any time limit for them to tell you to pull it down.
The Lammas eco-village [1] in Wales is very similar to the one in the OP, and is one of the driving forces for this kind of movement (and the One Planet scheme).
[0] https://gov.wales/docs/desh/publications/090521susdev1wales1...