Maybe it depends which supermarket? I think I heard about this anti-sprouting stuff from hearsay, maybe things have changed?
Anyway, if potatoes for eating sprout so readily, is it worth buying expensive seed potatoes from the garden centre?
Or maybe they don't breed true? I think they do: what we've got are, I think, variety 'Wilja', and it was the same last year. A large floury potato, easy to clean, good flavour, ideal for jacket or mashed.