Excel is more durable than a human can be, but I can't say it's "better" than a human within the context of "better" meaning the capacity to be truthful. An excel sheet is a source of truth, but the quality of that truth is not something excel imparts.

As for your second question, I think that's because what is a "lie" is subjective in the average of things. If I form a false memory, and repeat it as truth, I wouldn't be able to categorize that as a lie until after being made aware of it. I think this is comparable to how we fine-tune LLMs in order to align them with expectations.