Humans drink human milk, and the milk of other animals. Animals drink the milk of their own species on a regular basis. I will never understand why people get hung up on this in Zootopia as if drinking the milk of other creatures OR the same species is something humans and animals don’t ever do in real life.

Humans don’t usually sell their own milk to others or turn it into processed foods; it’s reserved for nursing their own babies. There are no lower animals in Zootopia, they are all anthropomorphic and behave like humans. So them having ice cream is akin to human women selling their milk for the masses to consume. It’s a little strange.