I think the tent city happened gradually not in 4 years. The dude was a hoarder. Takes time to gather stuff. And we are talking about a child here not an adult. That being said lets see how adults have handled similar situations - lady in the box was 18 and yet she felt she was a prisoner. She was even made to believe that she was legally the person's slave. She was allowed to visit her parents after only what 3 or 4 years and did not cry for help. Mentally she was a prisoner. There are other situations when adults have become mentally captive after being held physically captive. Even Katie, at 24, nearly did not yell for help when the police officer arrived, thinking it was a trap and not a chance for freedom and that was merely hours not years. Again we are dealing with a child when taken not an adult. So to mentally enslave them would be in fact easier.
It is easy for one, who is home safe, warm, surrounded with people who truly love you, sitting behind their little computer to say "if this were me I would have...." whatever dude. Safe, warm, with loved ones is not the same situation these people are stuck in. And a 11 year old girl is totally powerless against a man, who at the time was never two feet taller than her, or perhaps over two feet taller.