Well, to have milk, the cows have to get pregnanat regularly. The calves are taken away, which is kind of traumatizing. They are often not treated well. The male calves are killed for meat. Also, despite the fact it is possible to use transgenic bacteria, cheese is still produced in many cases by adding calf stomachs as a rennet, so cheese is often not even vegetarian. The real well being of milk cows is also often not as nice as one would expect, despite the fact that stress spoiling is a thing. Turns out some stress level doesn’t matter and some workers don’t mind the risk and enjoy the cruelty. There have recently been some cases made public in my country, so I’m more informed then I’d like to be.