In the United States, at least, the premise of this question is incorrect. In the US, college tuition has risen faster than the general rate of inflation for decades and has risen especially quickly in recent years.
Perhaps you can relate this to the topic at hand by saying that it is a lack of ability to mass produce and standardize that prevents college tuition in the US from dropping. Students who go to college expect (so far, at least) courses taught to them by professors who make up the course content on their own. They do not want instructors who are teaching from a pre-made curriculum. This type of thing reduces the colleges' ability to reduce costs through mass production and standardization.