So why didn't Mike and Terry just steal Ben's car and run for it? Were they getting off that much on bullying Jane and the farm family so much that the thought of just running for it never crosses their mind?
IIRC Terry wanted to do just that, but Mike was waiting for Al. Also, IIRC, she all but called him an idiot for it.
Re-watching the episode: it was Mike who wanted to run for it and Terry who wanted to wait for Al.
And why did Jane keep quiet about the robbery? Who was she protecting? Terry - the girl who set her up with attempted rapist Al? Herself, from the wrath of Mike and Al? Why didn't she at least tell her parents the truth? Yes, the real answer is "There would be no movie if Jane wasn't naive and kind of stupid," but still!