It definitely helps the breeder more than the owner.
The owner gains what exactly for most tests? Once you buy the dog, my thought is that its now your gamble. I guess you could try to enforce the health guarantee, but at 2, you're now rather attached to the dog. I don't really see the benefit unless you plan on going back to that breeder.
The breeder however, gains data on their line. They can also now advertise that they had all the puppies test clear, and raise the price even if they don't pay a cent into the health testing. So, basically, its the same thing as the breeder showing, it proves their dog, so either take a loss on it, or charge more.
Hopefully they could find a bulk discount with their vet, since they're already spending enough there.