>>5007645Obtained via very different means
Appear different when preparing... which is something very important that you're scoffing at for some reason
Historical precedent, both via religious institutions and cultural ones
Ethical factors; some people believe only warm-blooded animals, or only tetrapods, or etc can feel pain or think fully, so something like fish are fine. Similar exceptions are made for shellfish, or similar.
Definitionally; as some people have historically defined vegetarianism as including the ability to eat fish.
Not sure why this is hard for you to grasp. Vegetarianism itself is pretty retarded, so the people that decided that fish was fine were doing themselves a favor.