Maybe not, I cannot know. However, without a law, many people do commit adultery. With a law, many people do not commit murder. People are not naturally inclined to refrain from killing others as history tells us.I don't need a law to keep me from committing adultery and/or murder.
If you want veganism to be a simple in-group thing where vegans don't eat meat, then my explanation doesn't apply. On the other hand, if you see it as an overall moral belief about how to regard other species in all of our interactions with them, then it might.I also don't see veganism as a club trying to keep some in and others out. I never saw it as complicated. Carnivores eat meat, herbivores eat plants, omnivores eat meat & plants, pescatarians eat fish, vegetarians eat dairy, vegans avoid consuming animals, etc.