As far as I'm aware, they're not legally required to fortify, but once it's labeled as "enriched macaroni product," it has to meet the required levels from the standard.

This isn't unique to imports: standards of identity apply equally to domestic products. It's just that the FDA has tools at its disposal to block things at the border, which they used here.

> It's just that the FDA has tools at its disposal to block things at the border

This is a by-the-book example of selective enforcement.

It's not "just" a glitch. There are business interests for millions at play pushing for protectionism.

I claim no expertise, but from what I got reading articles on the matter, pasta in the US should be modified (fortified) to comply with regulations.

I certainly could be wrong, but I'm pretty sure I'm not.

There's a standard for both "enriched macaroni product" and just "macaroni product." I don't believe anything requires you to choose the enriched one, other than the fact that doing any enrichment kicks you over to the "enriched" standard and you're then locked into at least a list of several mandatory enrichments.

Some states have laws requiring enrichment of flour, bread, pasta, etc. though, and that I think is what's happening with even importers opting for enrichment: it's necessary to have access to a nationwide market.