You pick a % to keep and a % to pass along to each of your your dependencies, and then they split up that % that you passed along to them, so on and so forth.
Of course people could choose to pass 0% along to their dependencies. But that seems fine; people can adjust and just not send greedy projects a very big split.
Trying to enforce some fairness on the outside will probably just result in silly behavior from greedy people (ie, if every project gets an equal split out and somebody doesn’t want to hand any money down to their dependencies, then they can just create a bunch of tiny projects to dilute their out-split).
EDIT: I may be missing part of the point
Since you are the one marking the dependency of LegitimatelyUsefulLibrary on your PadLeft projects, you can game the metrics however you’d like when making it.
Trickle down economics? Ronald, is that you?
We can work on improving things later.
That is to say, I don't think a pure "frequency of use" metric is sufficient to fairly distribute such a pool. And if you have a large and growing pool of available money then the incentive to game the distribution scheme becomes more attractive than making truly awesome software. And I very much doubt that we have any reliable ways of aligning such a money distribution scheme with the goal of creating amazing software.