The "cost to supersize" seems to me (but I have no proof, maybe I have more money now) to have gone down relative to the meal cost, so it's more and more of a "no brainer" upgrade.

Maybe if they were required to price it backwards, where the meal costs $x and you can get a ten percent discount if you order small, that would "trick" people into eating less.

I received one of those paper sleeves the last time I went through a drive through maybe 4 or 5 weeks ago, but that's not to say the sleeve itself didn't get larger.