i think looking at a project that does use machines provides some context:

World Bicycle Relief has designed a bicycle that can be produced cheaply and be robust and easily maintained by people living poor rural areas. But only this would just result in people eventually having broken bikes and not knowing how to fix them or have the tools and materials to fix them.
So an equally large and important part of it is that they train maintenance workers and help set up local repair shops, and set up a structure so this can then sustain itself and spread over time.

now imagine doing this for a tractor instead of an analogue bicycle: it's just not happening any time soon.