"because what are the Dutch going to do, chase her down and shoot her ? "
No, but if someone her age has access to a bank account and can withdraw $5,000 (or euros or whatever) from it...in many places a prosecutor would go after the parents on contempt or conspiracy or other related criminal charges, and getting that news THAT could really put a crimp in her plans.
Slipping out the back door might be effective--but only if it was very carefully planned to prevent collateral damage. And then when she tries to clear into her first stop, well, someone might match up her name on a list and send her home under arrest anyway, leaving her new boat hanging on an impound dock someplace as well.
Not knowing the details...we can only guess that her memoirs will fetch a better price as the story gets more complicated.