Academic literature is expensive.
Now, a great many academians post their work for free, on their websites for their own reasons. In most cases, it is because publication is largely a publicity act. Others want to see their work spread. Others think information should be free. Whatever their reasons, some do.
Some don't. They largely do not see the point.
Whatever the acts of the individuals, academic literature is expensive in its published form. If you go to ScienceDirect, the price for a single article or book is steep--over $30. You have to dig for the prices too: http://www.info.sciencedirect.com/buying/individual_article_purchase_options/ppv/
Journal prices are similarly expensive.
There is just one catch: almost all academic research is funded by government grants. Why, as a tax payer, should I have to pay over $30 to access a paper that I paid for in the first place? Private researchers and private journals have every right to control the prices of their wares--but the academic world has no business charging for anything more than bandwidth (pennies per download) to an American citizen when working on a United States Federal grant.
Of course, none of this would even be a theoretical concern if we respected the Constitution's limitations and left the funding of research "to the states and to the People."