The analogy is poor because the point is that temporary unemployment of the kind you get with a noisy IQ measure is much less harmful than long-term unemployment of the kind you might get with a better measure.
The analogy is intended to be about reasoning processes, not the decision itself. Complaining that some readily identifiable people are hurt by measure X is a distraction if what you care about is total social welfare: if we can reduce harm by concentrating it, then let us do so!
I also think that, on the object level, replacing "long-term unemployment" with "long-term underemployment" significantly decreases the emotional weight of the argument. I also think that it's not quite right to claim that the current method is equally inefficient everywhere- the people who test well but don't school well, for example, are the readily identifiable class who suffer under the current regime.
Long-term underemployment still tends to erode, or at least not build up, one's skills, reducing that individual's lifetime productivity.
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