Coo for cats.

It's often stated that humans are the only animals which drink the milk of other animals and that doing so is an aberration. That's not true, but I've probably missed the point.
Cats will happily drink the milk of other animals. Hedgehogs famously too. It's not particularly good for them, or us, perhaps, but they don't find it distasteful. At all. They fucking love it. I've watched them fucking loving it. Cats don't consume what they don't want to unless they are starving or forced to. In moderation, it seems fine to me.
Birds too. When we used to have milk delivered to the doorstep, you'd often find the foil caps had been pecked open by sparrows looking to get at the contents.
I reckon if cats knew where to get cows milk from, they'd go and get it themselves.  The fact that it's in the fridge, closed and out of reach is normally deterrent enough. The fact that it's in the shop, closed, on the shelf, and you need money and cats don't have pockets is often deterrent enough.
The fact that it's in an udder, on a cow, in a field, out of reach, and requiring the deft touch of (for example) a milk maid, or a young cow, or the relentless tug of the automatic milking system...deterrent enough. You need opposable thumbs and the soft pliable pad of simian digits, not the slashing, slicing, tree climbing talons of the feline to coax the juice from the coo. If they could do it, if they knew how, you bet they would.
...or would they?
Dogs have owners, cats have staff, right?
Because indeed cats do have a tool for the removal of milk from cows. Us. With the opposable, pliable simian fingers and automated milking systems. With our bottles and complex waxed card containment devices, with our just out of reach refrigerated storage cupboards. Just as we might turn a tap or lift a cap, the cat operates us with a figure of eight around our legs and a swish of the tail, and lo, there is milk in a bowl, but not too often, because it's bad for their little tum tums, and we'd find ourselves cleaning up behind them too.