> For reasons I've never understood, many Americans seem fixated on viewing poverty and homelessness as MORAL failures, which deserve punishment.

I think you slightly misstate it: they view poverty and homelessness as an outward evidence of moral failures (particularly, an insufficient work ethic) and (often, though this view is sometimes found divorced from religious judgement today) divine disfavor, not as moral failures in themselves.

This has been traced back (both by people who view this attitude positively and by those who view it negatively) to various elements of theology of various strains of Protestantism that shaped American culture, particularly the Puritan concept of “visible saints” whose outward signs were wholesome living and material success.