IMO there are puppy mills, and then there are puppy mills. It is very unfortunte that the very organization that is supposed to be making sure that these animals are taken care of, the USDA, is the very same organization that forces breeders to create puppy mills.
If you have over (I believe) 3 breeding females, then you are supposed to house them in a sepasrate building thasn the family. Eho ae the looking out for, the dogs or th family.
Not every breeding facility, that is registered with the USDA, is bad, some of them take very good care of their dogs. But it is a shame that breeders have to break the law in order to keep their dogs in their houses.