Twitch doesn't need to be the exact platform, but a metaphor: streaming, publicly-accessible video services, available free to nonprofits or for money from businesses. Volunteer watch groups.

I'm imagining a streaming platform that shows videos from various animal-related businesses and nonprofits. Animal shelters can sign up for accounts for free, farms and slaughterhouses can sign up for a fee. They can get some level of authenticity about their claims of being animal-friendly because you would be able to see the animals yourself and how they're treated.

Of course, the locations would need to be scouted by some outside group to make sure the cameras actually cover the whole area, but that doesn't seem too difficult. The real problem is that multiple video streams will need to be monitored, but security services already have a good model for that. Many monitors with many video streams each playing in real-time will allow someone to effectively watch an entire farm for a few hours. Volunteer groups that truly care about animals can set up a few users to take shifts.

As they say, "sunlight is the best disinfectant", and streaming video has never been more accessible, either on the streamer or viewer side. The economic incentive for farms to pay for this service (and the initial camera set up, and ongoing internet fees) are the same incentives that cause them to put terms like "organic", "free range", etc. on their packaging: customers want the animals they consume, or whose milk they consume, to be treated well, and are willing to pay for the better labels. This system allows customers to say, "Oh yeah? The chickens are free range? Prove it. Put a link on your egg carton where I can sign on and watch the chickens run around."