We have a farm. We had mice/rats. Now we have cats and very few mice/rats. Hence why they are barn cats. And our resident owls do a lot more to reduce the bird population than our cats although I'm happy when any of them kill the damn pigeons.
Our barn cats have all been cats that were dumped or found their way onto the property. When a stray shows up, they get fixed and can stay as long as they want. I have 4 outdoor cats now. It's not a bad life for them. They are fed 2x a day, always have water, they're fixed, dewormed, get their flea meds, go to the vet if something is wrong and get to hunt and since our property is enclosed, they don't need to worry about being killed by a stray dog or a car or starving to death. And they seem quite happy snuggled up in the hay loft.
Like I said, I would always prefer a cat have an indoor home but being a barn cat is a lot better than the alternative that these cats faced.