How editors vet a source before citing it.
Before a claim makes it into a reputable outlet, someone checks it. Editors look for a named person with a title they can verify, data with a stated method and sample size, and a track record that does not contradict the quote. On bigger stories they corroborate against a second source.
This is why manufactured expertise fails. An invented persona has no LinkedIn history, no prior coverage, and no colleague who picks up the phone.