@ZipLine-- My mother in law buys fertilized eggs. She says that if eggs are fertilized, it means that the living conditions of the chicken are better. Because in commercial egg producing farms, chicken don't have access to a rooster. So she actually believes that the chicken that these eggs come from are treated better.
Also, I've seen cooked and raw fertilized eggs and they look the same. So I think they are collected as soon as they are fertilized. A chick is no where in sight. But I understand that many people would find this unethical.
Fertilized eggs are sold because there is a demand for them. People who think like my mother in law may buy them. As far as I know, in some cultures, fertilized eggs are commonly used for certain dishes. So people may be buying these eggs for this reason as well.