It's still not obvious to me why a 17-year-old American being held against her will in an English-speaking country couldn't figure out some way of asking for help.
Even on a private jet, they'd all still have to go through some kind of immigration and customs controls, which would involve interacting with uniformed government agents on both ends of the trip.
You sound very uninformed about the psychology of coercion. It's clear that there are lots of things that aren't obvious to you!
What about Elizabeth Smart? She was held in her own country, never trafficked across any borders and regularly interacted with the public - in at least one situation she interacted with a law enforcement officer. Do you believe she wasn't being held against her will?
https://en.m.wikipedia.org/wiki/KidnappingoffElizabethSmart
Why do you think coercive control has been recognised as a form of illegal abuse in any relationships (never mind those with significant wealth, power and age imbalances) if it's so easy to 'walk away'?
That doesn't mean she couldn't have been forced to have sex with Andrew or anyone else, but it does strongly suggest that she wanted to be where she was, with the people she was with, and wasn't being held against her will.
Like Elizabeth Smart you mean? Or Steven Stayner? Do you think they wanted to be with their kidnappers?
What about women in abusive relationships? Why do you think it takes on average 7 attempts for them to leave? After all they can speak English and seek help easily. They're usually resident in their own countries. Why don't they seek help from officials? By your logic intramarital rape should essentially not exist (or at least never occur more than once), but we know that's not true. So why is that? Assuming your assumptions are correct?
Unquestioningly repeating "Trafficking! Trafficking!" as an answer to every question raised by the circumstances isn't doing anyone any favors here.
Neither is ignoring the fact that this is a well-recognised case of human trafficking in order to focus on your own uninformed assumptions. 
@PurpleOkapi
I'd be interested in hearing your answers to my questions
Unsurprisingly the rape-apologists @Pixxie7 and @StapMe have popped up to join in to - also feel free to answer my questions too.
It'd be great to see you engaging in deeper cognitive processes than simply 'blame the woman'