> "at best, the protein can sometimes be inferred from the nutritional information."

I looked at some recently in the UK and the nutritional information is always per 100g and says e.g. 11.5g protein. Is there something wrong with that meaning 11.5% without any inference, or are continental European nutritional information boxes presented differently?

In the US, at least in larger sized bags, flour seems to be treated as an ingredient and there might not be a nutritional fact label. I admit that I didn’t look that carefully last time I was in a European grocery store.

I imagine that the 11.5g you’re looking at really does mean 11.5%.