or, why pay money to go to college if all the lectures are available for free on the web?
Why buy a book when there is a Kindle edition on the web for free?
You are paying for the diploma, without which you will not be hired by any company for certain jobs.
If your goal is to be a Starbucks barista, save the money and listen to the recordings.
Because most students are far more interested in the degree than the knowledge.
You can check a book out of the library to gain knowledge.
Even thirty years ago when I was in school at a rather conservative university, the human sexuality class was nothing more than the university peddling porn.
The students are buying the package, which is deceptively labeled "knowledge". They would probably not be so inclined to spend good money on the product if they could see inside the package beforehand.
As for being free on the web, good instruction is already out there, just elsewhere.