As I understand it, the foxes were specifically bred to not just tolerate human interaction but to enjoy it and crave it. The thing is that that is selective breeding over the course of a couple dozen generations in less than 100 years.

Most of the animals that are currently domesticated have had thousands of years of selective breeding, so there are all kinds of specific behavioral or physical traits that they do or do not have.

Ironically, that kind of hyperspecific breeding for only a few traits is what leads a lot of modern dog breeds to have various health problems associated with their breeds because they are bred for aesthetic and not for health or longevity. A common example is the obsessive compulsive disorder bread into the dog that is associated with bull terriers or the hip dysplasia that is associated with German shepherds due to being bred to have more and more deeply sloped backs.