FRAUD PREVENTION, and to give the buyer peace of mind.
It has come to many breeder's and buyer's attention that pups have been sold under the pretense of a certain parentage.
The strangest things happen. A German Shepherd that looks like a Rottweiler is DNA tested and turns out to be 50% Rottweiler, yet was sold for $3500 as a pure bred GSD! A pup is sold as being a top show-line pup is purchased for $3500 plus many $$$ in addition and is DNA tested and turns out its Sire is a complete different dog/bloodline than was promised. Or, a small litter, but great combination, is born and the breeder has another litter of a lesser combination and adds that to the registration as being part of the better combination... (In the name of money, of course)
No matter what happens, your pup is UN-remittable when you discover this AFTER the fact. Sure, you may have AKC or SV papers, however, they are useless for show/breeding.
So, ASK for proof of ownership of Sire/Dam, akc litter registration and have it faxed or emailed to you before you send your money. Once a breeder does that, and shows where you can call the akc dna department for verification (tel nr: 919-816-3508), your pup will be remittable.
Since the AKC doesn't enforce DNA registration, except from imported dogs, then we, as responsible breeders, must do this to ensure 'quality control'.