Sure, and some wineries do label their wine as vegan, which is great. But this was about someone saying they only wanted to drink "real" wine and hoping for a

Sure, and some wineries do label their wine as vegan, which is great. But this was about someone saying they only wanted to drink "real" wine and hoping for a law that would require ingredients to be listed. But traditional wine production often uses fining agents such as egg whites, and it's not an ingredient, is not present in the final product, and would not be listed on a list of ingredients. So I don't really see the relevance. (If it helps, pretend I said Polyvinylpolypyrrolidone instead, which has no vegan concerns. Is its use as a fining agent a problem? Why?)