It seems that each tribe of elves has very quickly adapted Recognition to suit their lives. Go Backs don't apparently have Recognition because their lives have been much harder than even the Wolfriders, and they needed quantity to stay alive. It's hinted that the females can control when they get pregnant -- remember Kahvi's quest to find Cutter and get a child from him? She only wanted him for a day or two and then he could go back in wrapstuff. She had to have a reason for such confidence.