Scribe
Legend
What does that have to do with your implication that you don't need a roll to.convince a person?
If its obviously in their best interest, 'hey man, here's 10 Gold, enjoy' you dont need a roll.
If there is any possible way there could be disagreement, you are just as likely to get it from someone who is misunderstanding (slow/low mental stats, whatever) as you are from someone is objectively intelligent, but has come to a different conclusion.
"What bothers me so much about having the DC be based on a stat of the person you're trying to influence, is that it assumes the smarter, wiser, etc the person is, the less likely your attempt to influence them is to work..."
This makes perfect sense, because someone who is smart (Int stat) can absolutely think themselves into a position that in their view is correct, and the path of 'whats good for them' may not make sense to them because of the position they are in now.