Right now in the U.S. the dairy industry is working to enforce the rules about what products can call themselves milk. They are making the case that nut milks aren't really milks, because they don't come from lactation. Many agree with this decision because proper definitions in food marketing are important. https://youtu.be/JJCTIPWPNt
Other people think this is a silly waste of resources, and that people will always think of almond milk as milk, regardless of the rules.