I don't really see how 1:to many makes any difference in principle. Perhaps you were thinking of the amount of effort to help the many? As in 1:1 case it is up to the helper to decide how many resources, if any, to spend on helping. A society where the default position is that people deserve help is different from one that is based on the survival of the fittest.
Even if the default position is to help, it can't be unconditional, there are limits. You don't have a right to expect help when it places an unreasonable burden on the helper.
