There's a term in the industry that's used for the amount of sugar that makes a food tastier/more addictive while not making it too sweet, don't remember what it is though. But yeah, it's like you said, they add it to everything to make it better tasting and more addictive.

There was some lab-rat study super long ago where they got mice/rats addicted to sugar and cocaine, then let them pick between the two - and they chose the sugar every single time.