Good summary.
I've been to many foreign lands by myself. When I was in High School my French class went to France. I was 17 at the time. I turned 18 while I was there. We had chaperones and we stayed in a group. However, traveling abroad is not the issue here. The issue is whether or not she ran away on her own, or by force.
Having two daughters, I was deeply saddened by the reports from Aruba about the missing teen. My daughters are now 27 and 24 and both had taken trips while in high school and college. For the high school trips, they were chaperoned by school faculty as well as parents. The trips went off without a hitch and were a good learning experience for both. They were allowed to go because they had both demonstrated personal responsibility and good judgement. If I had children that were irresponsible, they would not have gone as they had not earned that privilege My wife and I told them that as we were growing up, we were told to stay in a group and leave no one by themselves; all in the group were responsible for each other. Above all, if something, a situation or person did not feel right, get away from it. While in college, both had gone on cruises during their senior years. My wife and I were a bit apprehensive, but at that stage of the game, you have to put your trust in them. They both had good trips and on their return, both said there was the potential for compromising situations either for themselves or their girlfriends, they avoided it due to WWMADD (What Would Mom And Dad Do). They still have a good laugh about it, but it gives us a comforting feeling that they were paying attention.