If any industrial crap is added it can’t just be called butter here, but must have a rider “Beurre salé, beurre aromatisée, beurre with added chemicals” etc.
Lurpak is made with fresh cream/milk so you would need to blind test the “extrafin” butters. Standard butter is made with frozen cream/milk.
I think a blind test sounds like a great idea. I love butter so would happily eat through a table full of samples.