You tell me where the consumption of dairy products must result in harm to the cow. I grew up around small-scale, subsistence-level dairy farming, it doesn’t inherently require any more suffering than either egg-harvesting or apple-growing inherently do.

A Jain doesn’t have to purchase milk from a factory farmer.

And AFAIK even the most stringent vegans don’t brush insects from their path with every step, or avoid onions and carrots because it causes death.