And indeed the planning board can make an exception:
A private road, but as with Class VI roads, only if the governing body, after consulting with the planning board has adopted a policy allowing building on that particular private road, or portion thereof, and then only if the owner has recorded a notice in the registry of deeds acknowledging that the town is not liable for maintenance...
So I would think that a farmer that wants to build a storage shed on the far side of his field would be able to get a permit as long as it's accessible by some private road (even a class VI dirt road)
Secondly, the project is not being marketed for specifically for under-developed countries. In the linked article they do mention their experience in Kenya and that one of their target markets are governments to support development projects or refugee camps. But they also state that they are targeting individuals in the US. Also their website makes it clear that under-developed countries are not the major focus.
This is Africa, dude.