duali,
Can you picture a scenario where the whole Girl Guide group is given permission to cross the U.S. border for a planned trip, except one of the girls, despite having all her documents in order, for the simple reason that she has a different-sounding name or is not Caucasian.  This has happened recently with numerous adults. 

So everyone else either continues the trip except for the little girl, or they all turn back BECAUSE the little girl was not given clearance.  What an emotionally-fraught scenario!  Not to mention trying to get refunds for any prepaid accommodation, etc. No wonder the Girl Guides executive has made the decision to just not go there!