However in fact I see a fundamental problem in my concept. It may not work in practice because there is a need at the same time:
a) for people to have tight personal relations and intensive personal monetary relations (personal borrowings, local business etc), without banks or other institutions involved. Only this way they will be able to judge confidently on each other.
b) for people to have understanding of modern financial instruments, understanding of long term planning, financial discipline and possible delayed consequences of their actions.

The a is not possible in the First World, people there rarely have direct monetary relations.
The b is not possible in the Third World, people there rarely have such understanding and long term plans.

So the a and b will never meet, and that's why this will not work. Unless there is a way to solve this that I've missed.

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There is the Second World between the First and the Third, but it will not work there either, because people there don't have neither a nor b.