My thought would be that it would be at the source level. "98% of people find this source reliable", though that's certainly subject to the same biases. Better

My thought would be that it would be at the source level. "98% of people find this source reliable", though that's certainly subject to the same biases. Better systems might require more work to mark a story as false (such as how reporting a story as false currently works in Facebook.) Over time, Facebook can see on their end which domains are pushing fake news and choose not to surface unreliable sources on people's news feeds.