I don't think she could have. She was 12 when she was taken into isolation and forced servitude, and prior to that had no real education, nor any opportunity for education after. She had no support system to teach her, train her, or help her understand what was possible. So her mind developed, between age 12 and
age 25 under threat of violence to work 20 hour days.
It isn't so much a question of being physically held against her will. Her prison was built inside her mind, and as the author demonstrates trying to teach her how to function outside the home, she could not have escaped her own mind even if she wanted to.
Like the elephant, trained from youth that the rope could not be broken, never again attempts to tug at the rope, she cannot fathom leaving.
It was only through years of badgering that she could finally unwind some of the patterns she developed and relax.
In my mind this is the worst kind of slavery - child trafficking and training them in a way that prevents them from even comprehending a life away from servitude, nevermind attempting it.