interference question

[CecilOne]

We have so many discussions about batter interference that it is obviously one of the hardest things to judge and call, especially in the instant of occurrence. There are often plays when the batter, either by position or movement, makes a play more difficult for the defense; and yet not all of them are INT. Even when the answer seems obvious in discussion, 99 shades of gray seem to exist in actual plays. Is it possible to boil these down to those always INT and those never INT?
Yes, I know the batter motionless in the box is not guilty, unless there is a play at the plate. The part I don't get is if the batter makes a perfectly natural movement out of the box and unknowingly gets in the way of the catcher reaching/chasing a loose ball or unknowingly gets in the way of a throw or the catcher attempting to throw, etc. etc. etc. Some of these seem grossly unfair to the batter; even if preventing a play/out by the defense.
Shouldn't the batter be treated the same as any other obstacle to the catcher like the backstop, umpire, her own mask, home plate or whatever?

All of this excludes intentional interference, it's just about normal actions with no intent to interfere. Also, this is kind of generic, no specific book in mind but only care about NFHS, ASA, PONY, USSSA and NCAA.