Sex is legal, but you can't go and buy a hooker.
A child isn't allowed into a pornography store, even though porn is legal.
Oxycontin is legal, but you need a prescription to buy it from the pharmacy.
I don't love the government, but this is one law that I can agree with.
Puppies and kittens are completely different from water bottles. First of all, they are actual living beings. They need to be cared for, and they can live well into their teens. You can go buy a puppy or kitten without even filling out an application. You can just pay for it and take it away. With puppy stores comes parvo, and other nice diseases. I'm sure that thousands of people are screwed over by petstores every year... tons of dogs from puppy stores die from parvo, intestinal diseases, etc, etc.
Once they are adults, dogs/cats that are unneutered can cause serious problems. They can create their own feral populations, and pop out kittens/puppies really quickly.
Not to mention, they can become a health concern, overrun native wildlife, bite/attack people, etc.
An unspayed female cat, her mate and all of their offspring, producing 2 litters per year, with 2.8 surviving kittens per litter can total 11,606,077 cats in just nine years.
You know who is stuck cleaning this mess up? In many cases it ends up falling back onto the government. Our county animal control shelter took in 64,656 dogs/cats last year. 13,434 were euthanized. At $60 a pop for an adoption animal, they aren't raking in the money. Tax payer money goes to this service.
I think that mills are the ones that mainly need to be targeted, but as long as petstores sell puppies/kittens, these mills are going to continue to exist and churn out cheap pets for big profits.
Yeah, selling puppies and kittens in stores is legal at the moment... but I really do think it should be banned.