I don't think 2 ways different plant oils might not differ much in their health properties suffices to conclude that the only difference between oils is taste.

I don't think 2 ways different plant oils might not differ much in their health properties suffices to conclude that the only difference between oils is taste. PUFA content and resistance to heat degradation (conferred by the antioxidants in genuine EVOO) come to mind. Neither of those is supported by an incontrovertible mound of evidence either, but it seems to me that there is enough of a possibility that this food choice can impact health that the consumer should be provided enough information to make their own decision -- or at least not lied to about what they're eating.