I believe that Pollard was punished in excess of what others in similar situations got and therefore his case has been argued over the years. However, he was an adult who knew very well what he was doing.
On the other hand, these kids were foolishly tricked into doing something for a payoff. Obviously they did not know it was drugs they were smuggling but must have known something was not quite on the up and up. Yes they should have known better, but they were foolish kids who made a huge mistake.