The Y-fold shrinkwrap is NOT always true. I've seen some definite exceptions to it. Case in point: Silent Hill 4: The Room. Virtually every copy I ran into in the wild had the heat seal shrinkwrap, but this was because they had a second copy of the instruction manual(in French) up under the shrinkwrap.
There are also some other exceptions to the Y-fold shrinkwrap, but unfortunately I can't think of them at this point.