Huh? Processed ingredients don't generally get a pass on nutritional labeling requirements in the US. A bag of flour in a grocery store should have a label.

The European grocery-bought bag of sugar I have lying around has a regular nutritional label, including a list of ingredients. Spoilers: sugar is made out of sugar and contains almost 100g of sugar per 100g.

I checked some 25lb bags of flour (not from a grocery store) and they do not appear to have any nutritional facts label.

Ok, if they're meant to be marketed for food service, like a bakery regardless of who actually purchases them, then that does makes sense.