Sorry. Pet store is a business.. not a shelter. They are entirely entitled to sell pets, including purebreds if they like.
Why not say the shelters should do their job of finding homes for all their animals.. and the pet stores can sell the purebred pups? Why do you automatically think "pounds" are all bad? The pound up the road from me has been pretty darned good at rehoming animals and keeping everything clean.

I'm not saying bad places don't exist. I'm saying stop relying on those labels to say "wrong" and "right".

It's not the pet stores fault that people buy/adopt pups or dogs and then give them up to shelters. It's not the breeder's fault that someone buys a dog then decides later they want a new one and they "dump" it into a local shelter. No matter how much you try to research the new owner, sometimes they fool you, or sometimes they plain change their mind, or the economy makes them need to give up their pet.

It's akin to saying that all big breeders of snakes are evil mills and they should only sell direct to buyers and never supply pet stores with well-bred snakes. There's rescues with thousands of snakes needing homes.

People who WANT a dog, snake, cat, kitten, etc can CHOOSE to adopt from a rescuer, pay for one from a shelter or pound, or buy from a breeder, or buy from a pet store. Those people are then responsible for their pet. They are supposed to care for it. I'm all for encouraging people to adopt homeless pets from the shelter, but I won't tell someone they are wrong for wanting to buy a purebred puppy. I WILL encourage them to make sure of where that puppy is from, whether it's checking out the breeder or checking to see where the store gets puppies from.

One tactic I see locally is that large breeders 'farm' out the puppies to people so that it appears that the person 'selling' the pups only breeds a couple litters. They send pups to the flea markets with a person.. again, so it looks like it's just a person with a couple dogs. That encourages folks to buy pups, and they will never know that the pups came from a large commercial operation, sometimes with very inhumane conditions.

The way to stop inhumane treatment of animals is use the existing laws to punish people who don't give humane care to their dogs. Don't worry about how many dogs, or whether they sell the dogs, or "adopt" the dogs, or keep them forever as a no-kill shelter. Worry instead about whether the dogs are being given proper shelter, food, water and vet care.

Labels like "pound", "shelter", "no-kill", "petstore", or "puppy mill" don't tell you whether the animals are cared for properly or not.