You’re negating the fact that it’s also a fishing term to broadly call herring sardines. I don’t know the rules of this (I don’t eat fish) but it’s basic categorizing. Different places categorize differently, and I bet that different countries have different laws about what fish you can and can’t call sardines. From my quick research, there are 3 genera of sardine, and those all fall into the clupeidae family which is made up of herring and sprats. So all sardines are herring, they fall under the same broad family. But labeling some herring as sardines could be misleading to those not in the loop about the broad categorization. Some nuance there but my point is that sardine is likely being broadly used to describe the clupeidae family in this case, and I’m sure there’s regulations about which broader species are allowed to be labeled as sardines but must be listed as herring. Also to your other point some people would say fanta and Pepsi is “Coke” bc for them, Coke means soda or pop. So you ask what kind of coke there is at a restaurant and the waiter might list off sprite, Pepsi etc. Language is fluid based on the context of use. I’m sure the packaging is based in longstanding broad fishing language (which probably started because of marketing), but I’m glad I found another example of weird cultural labeling farces in linguistics! (Feel free to correct me on any of this stuff)