Bird and reptile eggs are totally different. In bird eggs, the embryo is not attached to the shell - you will have seen from using a chicken egg that the yolk is loose and surrounded by the egg white. The yolk is the embryo, whichm if the egg had been fertilised, would eventually develop into the chick, with the albumen providing all the nutrients. The shell is also hard and so water loss/retention and oxygen transfer is not an issue. However, in reptile eggs, the embryo becomes attached to the side of the egg shortly after being laid. If the egg is turned, the embryo can become detached from the shell and die.
This is why bird incubators cannot be used for reptile eggs, as most of them have an automatic turning mechanism so that the egg is turned regularly. If this happened with reptile eggs they would all die.