It’s kind of funny, having the calves slaughtered to get the milk that is naturally meant for them is considered vegetarian (as long as you personally don’t eat the veal).
If they’re kept on abusive factory farms, that’s still vegetarian.
When the dairy cows gets their throats slit because milk production drops below profitablity after ~5 years, the milk is still seen as vegetarian (as long as someone else buys the meat).
No matter how much death and suffering takes place at the farm, the milk is seen as vegetarian. But at rennet, that’s where they draw the line.