There wasn't a common mistake in that case at all. The doctor represented that he had knowledge that I didn't have that led him to conclude that the insurance would pay for it. I had no way to check his reasoning. The point of that example is to see that you can't stop at the contract -- because my prior agreement with the doctor made me responsible for any costs the insurance wouldn't pay, his false representation (one I had no way to check nor any reason to doubt) damaged me.

This case is totally different -- Patrick substantially explained the reason he reached the conclusion he did, gave all the information needed to verify it, and she agreed with his reasoning even though it was obviously incorrect. The whole point of the discussion was to protect against indirect Pirate exposure and they agreed that if that Patrick had no direct Pirate exposure, that somehow meant there was no indirect exposure.