A, D, X, and Z also limit dealership "administrative" fees to a reasonable $100. Very YMMV as some states limit these fees and others just let dealerships run wild. Jalopnik (I think) had an article where a Florida or Colorado dealer was getting like $800 a sale in excessive official looking fees. F&I guy was described as auctioneer style in getting documents signed.
With plan pricing the dealer is also forced to show the exact amount he is allowing for your trade - "actual cash value" something you won't find often in a traditional sale where over-allowing and smoke/mirrors and number fudging are more common place.