Too bad they're illegal to keep in Sweden. (You can have elephants and dolphins, but not foxes or small wild cats.) And I think even if the government knew about domesticated foxes that do as well in captivity as cats or dogs, they wouldn't be legalized, to protect the real wild foxes from the trade, or for environmental reasons (same reason falconry is illegal - so the birds won't affect the wild birds of prey).
but it's an actual good reason; if the domestic foxes were to escape and breed with the wild ones, they would destroy their red coat genetics by bringing in the ''domestic colors'' genes, etc. and tamer behaviors that would make them curious towards humans, which might lead them to death (shot by hunters)... and it's because foxes (vulpes vulpes) usually live in Northern regions, where winters are pretty cold. Their tail, which are 75% of their body length, help keep themselves warm, and protect themselves from the snow and wind when they're sleeping (they curl up and stick their face under their tails!). Unfortunately, most people see fox tails as wall hangers or fur coats, and that's why so many foxes are harvested for their fur - 
