Kidnapping for ransom is rare in the United States. It's not good risk/reward. The family of the kid enrolled at Le Rosey is probably living beyond its means, and lacks sufficient credit to pay enough ransom to cover the costs of a kidnapping operation.

The only significant kidnapping in the US is drug-related (in Phoenix) or husbands kidnapping their own children from estranged wives: http://www.latimes.com/news/nationworld/world/latinamerica/l...