I think her experience is not that uncommon. Statistically speaking the risk of meeting a young guy on an island, a guy from a middle class kind of family, at age 17 and talking with him and taking a ride is probably not that bad.
When I was a teenager working summers on Martha's Vineyard, it was common for kids to hitchhike everywhere on that island. That was some time ago, so don't know if it's still the case.