Think about it as if its about consent. The bees don’t consent to their honey being taken. Cows don’t consent to be repeatedly impregnated and milked. Pigs don’t consent to their butts becoming bacon. Chickens don’t consent to their eggs being taken.

However, the miller and the baker both consented to milling/kneading, and later selling their wares.

Human breast milk can be vegan, though, if given freely. If you forcefully take human breast milk, then it is no longer vegan.