The original claim was that we spend far too much on prisoners, and the rationale is that it costs 10x more per prisoner than per student without any regard to the actual costs and complications of doing each job. The fact is that prisoners are fundamentally that much more expensive to manage. And if society requires some violent and antisocial subset of the population to be removed from the rest of society, then this 10x cost is justified as far as I can tell. I'm offering the geniuses of Hacker News an opportunity to show that they can do it for less, since they seem to know better on this topic.
The original post just highlighted the very high cost of imprisoning people relative to other things one might do with the same money. I see no suggestion in it that it ought to be cheaper, though there's perhaps an implicit suggestion that the US might want to reconsider having the highest per-capita prison population on the planet, since it's so expensive.
> I see no suggestion in it that it ought to be cheaper
So, it's both "so expensive" and there was "no suggestion that it ought to be cheaper?" Cool. So, what in his inkblot of a post did you read as the solution to keeping violent criminals from subjecting society to their violence?