I grew up in the dairy industry. Any farm that utilizes animals involves some innate cruelty (even animal rescue or animal sheltering can involve cruelty), nonetheless, what has occurred in the dairy industry over the decades is an outright crime.
We didn't live on a farm, but I visited farms with my dad, who was an artificial insemination technician, and with my first boss, who was a vet. I also stayed on farms during the summer when I was a kid.
Big corporations have made it difficult for small farms (where cows at least go out the pasture for a large portion of their day) to survive. Cows now spend their entire lives in muck-filled barns and yards, and male calves, who are worth nothing as milkers, are trucked off into the crate-veal industry instead of being put out to pasture for six months and killed for beef. The end result is the same for the cow, but the life in between birth and death is radically different.
When I grew up, ear-tagging was one of the most inhumane parts of dairy work. No farmers I knew would cut off a tail. Tails were vital to the comfort in the cows so they could brush off flies in the pasture. The cows were even wiped down with fly spray so they were more comfortable in the field (comfortable cows = more milk, back in the days before hormones).
It was still a brutal place. Cows would get mastitis. If they got ill and "went down" getting them back up (so they would live) often involved beating the cows up horribly. When I worked for a vet, I watched the vet go after a downed cow with a pitch fork to "get her up."
And any animal business can be victim to those human beings who, out of anger in their own lives, take it out on the animals.
This ABC News blog post will provide a glimpse into what large-scale farming is like.
While the outright one-person cruelty is hardest to watch (even I had to turn it off) in the first video, it is the statement of the farmer put in the position of having to say whether or not a cow feels pain when her tail is cut off without anesthetic that is most telling (the second video).
When you are exposed to cruelty over and over, you begin to tell yourself it's "all right." This can be true in sheltering and rescue, as well as industry.
The fact is, any time you work with animals, if you allow yourself to become a victim of irrational thought ("it doesn't hurt cows to cut off their tails" or "our cows that are confined 100% of their lives are happy healthy cows") the animals in your care are literally victims of your cruelty.