This is not about not having documentation in order.  

And it's not about individuals not making the trip for a variety of reasons (ill, parents can't afford it, etc).  It's about individual girls being prevented from entering the US even with proper documentation.  We've already seen examples - the Canadian citizen (Canadian born) travelling on a Canadian passport being detained for two hours and then turned back and told she couldn't enter without a proper visa - her "crime" - being brown skinned and having a Hindu sounding name.  The high school math teacher who wasn't allowed to board the plane to accompany his students on a trip to the US.  The women who were quizzed about their opinions of Trump and then turned back.  The list goes on.