Do you know why the mounds with half-moon shapes? Why is it more effective than simply digging a circular hole in the ground?
It's an ancient practice that was forgotten and rediscovered. The beauty of this approach is that it shows results within a few short years. Basically in Africa if there's water, nature shows up and consumes it. So you get lush growth and rapid soil restoration. Trees, vegetables, etc. on what was a heavily eroded flood plain before.
It's easy to explain, the locals get why it works. And they get a very fast response from nature and all the produce and riches that come with that. And all they need is shovels and some elbow grease.
Most of these ditches are dug out by the locals with shovels. We're talking subsistence farmers here in areas where people are more or less trying to live off the land. Their hands and some primitive tools is all that's there.
I would still call people using bigger stuff to be doing manual labor. For the same reason that using a lawn mower is still a manual labor job.
I imagine they /want/ it, it would just be a massive issue because they do not have equal supply chains to more developed nations, and them having to pay to make up the difference makes the cost-to-benefit ratio not make sense