I hope they know what the neck area constitutes as by a single definition or that leaves rules open to interpretation.
They lose their value as a standard to play by if they're open to interpretation on what each body part is.
I understand that judgement calls are needed because of the speed of the game however a body part should be defined by definition and the only judgement involved is if the referee correctly saw what he believes he saw.
I see "neck area" and I believe it is the area containing the neck. You see "neck area" and believe it is the area around the neck. Those are two different things. One definition makes hits illegal to the upper shoulders and collarbone as you put it while the other only protects the neck itself.
You're right, not everything can be black and white, but a strikezone needs to be.