Is that what enriched means? Is that all that's added B vitamins and iron?
Basically. It's to bring the nutrient levels back to what they were prior to the grinding. When I did R&D for a flour mill they added back some vitamins and iron mixed in with barley flour as a bulking agent. It's pretty common and basically an industry standard. I highly doubt it has any legitimate effect on anyone's actual health but it's just kind of "what you do".
I hate to speak ill of my former industry but outside of very specific people (think Jewish bakers who demand first clear to blend with rye) the average flour buyer has very little knowledge of what's in the bag. Protein, ash, falling number, and other important details are never reported. You're lucky if you even know the blend of wheats (white/red/summer/winter).
I'm most curious if this is a trend to cut costs or just one-off. The brand is Great River Organic Milling 100% Organic All Purpose White Flour.