Specificity. It's an existing exception in advertising law (or so I've been told). Anyone can claim "we have the best burgers" -- and many restaurants do -- because it's non-specific. Ironically, if you were to attempt humility by claiming "we have the second-best burgers", that becomes a specific claim, and you'd need research to support it.

"The Governor of California is sending Ballots to millions of people, anyone living in the state" is a specific claim, and would need to be supported. It's a different category of claim than merely boasting "I am the best president".