I find it extremely unlikely that a restaurant would accidently serve bluefin tuna calling it yellowfin. The main reason is that bluefin is incredibly expensive, costing many thousands of dollars for a single fish. They are sold at auction to knowledgeable buyers. Second, the US serves very little bluefin, as far as I understand; partly because Americans don’t have a strong appetite for that type of fish, but also because some enormous fraction of bluefins are sold to Japan.

I should mention I learned this from a recent edition of NPR’s science friday; I highly recommend finding the episode.