Given that much of the funding will never be repaid, assuming it is targeted at the most needy, we should look at how to optimize the value proposition in other ways. I do not think that laboring under a debt burden is a good start point for new workers; think of student loan problems in the West and how they create significant stress at a time when we should be encouraging positive thoughts on building a future.
The overall funding we see, as mentioned, comes from a variety of sources, depending on circumstances. Family assistance will always be an important factor - and one to be greatly encouraged - as it has its own personal monitoring. It can also be considered as having an implied debt for those who become successful to hand onto the next generation.
Our core aim of moving to reportable, real time transactions at all levels of society, is so that taxes, duties and fees can be collected by the government in a manner that is seen to be open and fair. That is where 'repayment' can be generated, from those who are capable of building a business that reaches a stage where it can afford to be taxed.
The key aspect of tax collection is to manage it in real time. Wages should be calculated centrally, whether from one employer or many for any individual, with the net settled in conjunction with any other funding sources. Just as importantly, VAT or Sales Tax, should be deducted from the settlement of the clearing of an electronic payment to a merchant or service provider, so there is less room for evasion.
(One separate but attached point on this collection method, relates to the capability of showing suitable respect for the confidentiality of each individual's financial circumstances. The merchant may sell goods at 100, of which VAT is deducted of 10, so the merchant receives 90. The purchaser will have transacted for 100 with the merchant, but may have been entitled to a significant reduction - based on product type, financial circumstance - and only paid 50 at the central clearing point. So, the government will have lost its 10 tax, and the funding source will have paid 40, while the individual will have had complete privacy as to this structure.)
Returning to the question of repayment as a general part of the aid structure, I feel that we should look at the world as it is, rather than how we want it to be. The rich/ poor divide is widening in many parts of the world to a frightening degree, so much of what we see as aid is actually never going to be repaid. It is there to keep a very low floor under those at the bottom of the ladder, in terms of food, clothing and accommodation. But what it can also do is create hope through opportunity for individual achievement to learn and prosper.
To sum up my response, I look at fair, automatic tax collection - just from those who can afford it, as the best way to get 'repayment' of aid, assuming the government is held to reasonable standards of reporting, from those who have received individualized funding in one form or another. Of course, this does not address large scale projects, funded at government level, but it relies on helping the 'light at the end of the tunnel' for those who want to work towards it.
My final point is that the big hole in any such scenario is cash. As we see in the EU, with its $200 billion annual hole in VAT alone through evasion and failed collection, if you allow significantly large cash transactions to escape tax, you blow the system apart. When you have VAT rates that keep going up -now 25% is the norm - you have an ever-increasing reason to evade by choosing the black route. We must work harder to reduce this problem by ensuring we have a reliable transactional flow for everyone to use electronic payments.
Which brings us back