The calculations account for accuracy. The fact of the matter is, since rogues rely on one big hit per turn to keep their average damage per round up to par, missing has a much bigger impact on them than it does on other classes. With two attacks or one attack with advantage, they about keep up with the fighter. With one attack without advantage, they fall behind. Since this is a matter of averages, it probably won’t be noticeable on a turn by turn basis. The disparity in average damage manifests over the course of many combats.
And they aren’t the best damage dealers in the game. If they get two attack rolls per round (be they two separate attacks or one attack with advantage) with the potential to do sneak attack damage, they do about the same at-will damage as a fighter, but still have lower average damage per round due to lacking the damage boost the fighter gets from Action Surge. And that’s just the Champion fighter! A rogue’s average DPR falls even further behind subclasses that have additional damage boosting resources like the battle master.
Let me repeat that: the rogue does less average damage per round than the fighter, even with two attacks or one advantage attack per round. If they don’t get that, they fall behind even further.