Because it's 2022 and adults are unable to distinguish between want and need to the extent that some people behave as if owning a dog is a human right.
The idea that puppy farms make dog ownership affordable for low income families is ridiculous. The puppy farm owners breed the dogs is such deplorable conditions to maximise profits not to make dogs more affordable. The difference between a dog from a reputable breeder and a puppy farm is not the same as the difference between branded a supermarket products, you will pay the same wherever the dog comes from. Puppy farms are not offering economy dogs.
Some of those puppies are smuggled over in buckets or plastic storage bins, the lucky pups don't spend a portion of the journey with their dead siblings because quite a number do not survive the journey.
People are also easily fooled or do not do any research before buying a dog. The ads on pets for homes will all say the pups come from a family pet and the puppies can be viewed with mum but in reality the breeders rent a house, off load puppies from vans in the morning and the bitch you see with the puppy is a show bitch because the bitch that actually gave birth to the puppies is probably in a visibly shocking condition.
It's a disgusting practice and if you buy a dog this way you should be ashamed. Feel free to be offended, I don't give a fuck.