You can sort-of argue that there are examples of ethical milking if you just consider the direct action of milking, however if we look to the bigger picture of dairy production — which includes how the cow came to be and what the milk is intended for and why the cow needs to be milked — it becomes more difficult because dairy cows have been bred to produce more milk to the detriment of their health: you’d need to find an example of the more broad “ethical dairy production” and that’s a lot more difficult, as almost all dairy production builds on the unethical behaviour of the past.