The Real World: Cottages well as close as they'll get to its

"We certainly didn't think much about our lives beyond the Cottages, or about who ran them, or how they fitted into the larger world. None of us thought like that in those days." Kathy page 116
The characters in this book have their whole lives pretty much planned out for them. First they go to Hailsham where every aspect of their lives is run by guardians and other adults. Then once they are all grown up they either become carers or donators. But what about the middle adolescent period? That time is spent at the Cottages. The cottages are the closest thing to a real life that these teens will ever get. This is a place where they can do whatever they'd like, go wherever they want, and hook up with whomever they want. Not all the kids who stay at the cottages are from Hailsham though several all. They are normally separated into the new members and the veterans. In a way it almost seems like college. After all the characters are experiencing a sense of independence and fun. However, there doesn't seem to be a time limit on their stay. So why leave at all? Are they allowed to stay forever or does someone make them move on eventually. From what I understand they all just choose to leave but why? Why would you willingly just write away your life like that? But is that what growing up is like? I mean there are certainly a lot of negative aspects of adulthood but there always seem to be benefits that make us want to move along. But what are those benefits for them? I would really like to know what that would be for them...