As for your final point "I wonder if people are seeing what they think should be deductible on 1116 part I line 2 rather than finding authority for what should be deductible there."
The issue here is the authority you are referring to does not exist in certain aspects of 1116, line 2, as evident from different interpretations of the same section by different experts and even by your comments throughout this discussion. In the absence of this, naturally the conversation drifts toward "what should be" instead of "what is".
