>If you asked the person in the street "should companies be held to absolutely strict truth in advertising for quantitative claims", once you explained what it meant (!), I'd warrant the vast majority would agree, yes they should.

This overestimates support because you're vague on what the policy actually is, so everyone thinks that it's going to be their preferred variant being implemented. See: the brexit vote which got a majority vote for "yes", but in reality the none of the individual proposals got majority approval.