A lot of people don't understand that "factory farms" get franchised out to "small farmers." Big chicken producers hire farmers to raise their chickens. The smaller farmers take on much of the financial risk, employment issues, etc. So when someone takes video of bad practices on a farm, the responsibility might be on the hired farmer, or it might be on the big agra company that hired him but didn't pay enough for humane treatment and sanitary conditions.

The main issue is that often a farm isn't merely some small farmers property. It's the place where big agra policies are being enacted.

Few people would be outraged if someone smuggled a camera into a big factory to document abuses. Be skeptical of privacy arguments here. This is the equivalent of a big manufacturer contracting out to small sweatshops.