It’s oat juice, soy juice, rice juice, almond juice, coconut juice, ect., ect.; none are MILK.
Milk is produced in the mammary glands of mammals, nowhere else.
You do not “milk” a sprig of oats or rice, or an almond, or a soybean, or a coconut. You squeeze or mash them or mix with water to extract a juice from them. That is juice, not milk.
Because it is “white” does not make it “milk”.
A benevolent dictator, wishing to see language not misused to confusion, would declare “milk” as only to be used with respect to products from the mammary glans of mammals, no where else. The others can be called “juice” of some sort, not “milk”.
Are you insinuating that the soy plant doesn’t have a nipple?