The invisible hand only applies here if the goods are identical, and since we're talking about unique works like books, they are definitely not equal. What one another charges does not dictate what another author charges.
> The only people who can get anywhere with that are people who already have money or some sugar daddy (or mummy.) Many of us have to work to survive. Ever heard of the working class?
Wow, do you have any idea how many open source software contributors are living on Ramen and are on the side of the working class?