E-glitter, breeding depends on such a big array of things, that there isn't a simple answer to it. A lot of hobby breeders do end up with a small number of fry, simply because they just let nature run its course, without further doing anything to increase the fry's survival rate. The bigger ones eat the smaller ones, a lot of them get deminished by illness like fungus and flukes, so taking precautions against those things increases the fry number tremendously.
The amount and times of feeding is also very important and can make the difference between big and healthy, or small and sickly, little fish. The number of water changes, the quality of food, the amount of water the fry is in, and the list goes on and on.
As for pet stores taking the fish in, some will, and some won't. I have a couple of stores so far who are willing to take any babies in, but not every store has the same policy.
The general idea of why the book said, everybody should try breeding, has two aspects. First, its an enormous experience to raise fry for the first time, but there is a much bigger meaning behind the whole concept.
The true meaning of breeding is keeping the true breeds of goldfish alive for generations to come. So breeding is important, but not just any breeding. LEtting the fish breed with whatever breed is with them in a tank doesn't do much to that purpose, it rather has a negative effect because you are not truely keeping a particular breed alive. You end up with so many mix and matches that are having the genes of either one of the parent breeds, and if the breeds were different (oranda male, telescope female for example) then you will have more fry that are not true to either one of the parents breed.
There are enough lousy quality fish in pet stores as it is, and I am not too happy of people selling their missmatched babies and further bringing the true meaning of the goldfish down. The quality and standards of the goldfish were a lot higher just a couple of decades ago, while these days its "just" a goldfish. Which is partly to blame on all those low quality goldfish in the store. Not enough of those are true breeds, and are rather runts of some mismatched parent pair.
So, if you wonna go into the joy of seing little fry grow into a healthy and beautiful goldfish, pick parents that are the same breed. Chances of having healthy and not deformed babies are a lot smaller that way, and you will not release some runt into the general population. Breeding, after all, is a wonderful thing to experience....