It is illegal to create a monopoly in the U.S., with the exception of the labor unions, but that's a story for another day.
Free markets require competition for the benefit of the citizens, and laws were enacted during the era of the robber baron to ensure that no industry holds a monopoly.
For that reason, government lawyers are taking a close look at the deal that Google reached with authors and publishers. The book scanning proposal is intended to protect the owners of copyrights, but Google has set itself up as the sole holder of a vast expanse of knowledge.
Anything not held in copyright, commonly referred to as "orphan works", become the property of Google after scanning and uploading. So if they are the only business owning a given book, how much would someone have to pay to see it?
The idea of a monopoly is to control a given industry so that the industry, and not the market, sets the price. If Google controls the products that students need to prepare term papers or a thesis, how much might the search engine behemoth charge the college library for access to their stash?
What about your local library? How much could Google charge the library's taxpayers for permission to see things online? It's a convenience, after all. The scanned books exist in hard copy, but thumbing through an old journal might involve travel to Princeton or the University of Milan. Can't afford it? You're out of luck, then, with getting the data that you need.
Should you find a willing librarian to copy the required pages for you, are you then violating Google's copyright?
The U.S. Department of Justice has many other such questions, and they will pick apart the Google settlement very carefully. No administration wants to be known as the one that shut the doors on knowledge for all.