I disagree only with the grandparent post's argument that an administrative approach would be bad because a subset of people would be worse off under it.

I think that type of reasoning is fallacious because every policy leaves a subset of people worse off (you can just choose your preferred subset to make the point). Including the status quo.

I like your kidney analogy, and I think it makes a strong counter point that is worth considering when weighing up policy ideas.

Though, the status quo in that analogy looks to me like the majority of people in the world currently are having one kidney removed during childhood, mostly to feed the middle classes and build toys for them. Some unlucky ones have two; they are sick and dying. But we couldn't take a kidney from the healthy middle class folks to give back to those, could we, because voters in the middle class feel like they've worked (and continue to work) very hard to get their kidney from some unspecified source we don't like to think about, and they object to the meager spoils of their hard-earned spare kidney being taken for redistribution back to the people they came from.