Foxes are not commonly treated as pets, and for good reason; they are wild animals. By wild animals, people mean they haven’t gone through a breeding program for domestication, which dogs, cats, and various farm animals have gone through. This breeding process selectively breeds animals which are more friendly to human contact and are less likely to harm people.
A fox which hasn’t gone through this process makes a poor pet. While they can become tame, and accept contact with the person who’s raised them, they are still noticeably a wild animal.
Over a 50 year period, a breeding experiment has been running in Russia to determine the effects of selectively breeding animals purely for tameness. This has resulted in a domesticated silver fox, which makes a good pet. These domesticated silver foxes are neutered to ensure somebody else can’t set up their own breeding program, and are very expensive to buy. As a result of selective breeding, we can see foxes with whiter, thicker coats, shorter snouts, and more friendly temperaments.