I take it you're not familar with Prop 65? In California, you'll see that everywhere thanks to a well-intended but counterproductive ballot measure that introduced steep liability for anything that could possibly cause cancer at all, even if only egregiously mishandled. It's even on packages of food now!
It still surprises me that after 38 years of this obviously ineffective and wasteful proposition, no group has gotten around to putting a repeal on the ballot.
In California, ballot propositions are a form of direct democracy, and changes often require a referendum. Who has the time or money to campaign to convince voters to remove cancer warnings?