Marshmallow fluff is imported from the US and there's probably not currently enough demand here for the large quantities - so the smaller jars are all we can get without having it privately shipped over.
High fructose corn syrup - a principle ingredient is not commonly available in the UK because of European production quotas pre-2017. It's never been banned (contrary to myth) but UK industrial food production has tended towards mass production of different beet based sweeteners.
It's highly possible that this eventually might change - but until HFC syrup is embedded into food manufacturing and in commercial catering on a large scale it probably won't. Corn syrup has an incredibly bad health reputation and there's great enough resistance from the health lobby that might deter companies from increasing its use. As well as being cheaper just to carry on using the alternatives in the supply chain.
I've wondered about the possibility of making something similar, since it's essentially egg whites beaten with a sugar syrup (plus some flavouring and stabilising ingredients). That seems like it could be quite cheap to make at home with a more available syrup, though it would definitely need mechanical mixing. I might experiment at some point.
Love you, too
