If Obamacare fails, one sure political consequence is a revival of pressures for something more sweeping, for a single-payer program. Nowadays advocates of such a program in the US call it "Medicare for all." One of the points they make draws on the supposed efficiency of Medicare. Overhead costs are only 2%. Private insurance plans have overhead at 20% of spending. So the former must represent a better way of doing things than the latter ... right? Holman Jenkins made several valuable points about this in a recent WSJ column, among them these: First, the 2% figure is a dubious one to begin with, since Medicare's overhead costs are in fact picked up by other parts of the Federal government. Much of a private insurer's "overhead," for example, is bill collection. That portion of "overhead" for Medicare corresponds to tax enforcement so it is picked up by the IRS. The 20%, then, contains items the 2% doesn't. [Also, HHS' budget i...