Another dimension we have in France: most butter in 82% fat, but if are not careful you might buy so-called butter with much lower fat. Awful taste on morning toasts, ruined pastries.

82% seems the norm here too, good to know this. Anything lower is labelled 'spread' (based on a very quick search, maybe not always true here). Oddly specific, so maybe there's regulation at play. We prefer French butter for the quality and because it comes in the correct size.