This is not a case of me not reading the previous thread before commenting.

It seems much more like a commentary on the American prison system than anything else. The Western European systems don't generally suffer many of the problems of American Muggle prisons, or the problems they do share are often to a smaller degree. Britain is one of the middle range countries in this regard, but this may be enough for some people to not get the point.

Notice what this says: Western European prisons are so good that Eliezer's commentary is really only about American prisons. (Also note the implication that the Muggle world is partitioned into two regions: Western Europe and the United States.)

In my opinion, you're reading too much into the original comment. There are fewer Western Europeans in prison than Americans. Aside: their "Western Europe" is much larger than the traditional one, which already has a higher population than the United States, and so we can also say there are fewer prisoners per capita in Europe than the United States.

It'd be surprising if American prisons didn't tend to have more problems.

For all narrative purposes, the only regions of the Muggle world that significantly matter to the story are Europe and the United States, so your aside seems a misplaced criticism.

I more or less agree with your assessment of the metaphor, but there is no purpose to letting a poorly-grounded argument carry through just because one agrees with the conclusion.

To "correct" me on such a point is to increase the noise and decrease the signal.

Aye, but pray, where was the signal in the first place?