I live in a city that is about the same size as Dunkirk and would like this to be implemented (even though I walk to most places). I see this freeing parking places in the centre and that really would help with the dying local commerce in the zone.
For me the question is how are recipients selected? The main drive to use that API would be to promote doing the right thing, but for that to happen, recipient selection is a key aspect. Look for example at Kiva, you know where your money goes, why these people have been selected, and even may know how to apply for these micro-credits.
As for your questions, b) would be a demotivator to use it, and I think that 'feature' could kill the API easily on bad press.