I'm not sure it's so much that they weren’t smart enough or couldn't think something up. If it were you or I just put there in our current state of mind then I'm sure we could think of a way and get out. But these people were mentally fucked up. Imagine being locked up you whole life. Think back to a memory of you at 10 or 12 going to see a movie or your first baseball game think of your days on the playground at school. Now replace those memories with a dark basement and having this guy do god only knows what to you. The things in our past, memories, experiences, life lessons, all make us who we are now. If your life consisted of a dark basement and some sick fuck it would break you down and over a period of time you would just accept you fate. That’s a very sad, disturbing and screwed up situation.