And neither does any other search engine. Interesting:
Focus group and survey research indicates that undergraduate students typically turn to popular Web search engines when they need to find information. These search engines index only the “surface Web,” where less than 7% of the information is appropriate for educational or scholarly purposes.
No single Web search engine indexes more than 16% of the surface Web, yet we have no evidence that students use more than one search engine when they look for information. According to BrightPlanet, the “deep Web” is 500 times larger and growing faster than the surface Web. The deep Web provides information in all disciplines, for all constituencies, that is 1,000-2,000 times better in quality than the surface Web.
Approximately 95% of deep Web content is publicly accessible without fees or subscriptions, but deep Web content, like scholarly commercial resources licensed by the library, is not indexed and therefore not accessible using popular Web search engines. The growing concern is that many undergraduate students may be searching only 0.03% of the Web to complete their assignments, ignoring entirely the books, journals, databases, full-text digital resources and other scholarly materials provided by the library. Because of easy access to the Web, undergraduates are using library collections and services less than in the past and, in the absence of quality information and tools on the surface, this may imperil the quality of student learning. For this reason, some faculty members do not allow their students to use Web resources in class projects.
From Troll, Denise A. “How and Why are Libraries Changing?” Digital Library Federation. Library Information Technology- Carnegie Melon, 9 Jan. 2001. Web. 29 Nov. 2009. http://www.diglib.org/use/whitepaper.htm
A commentator suggests the numbers may be slightly old and inflated, but nevertheless.
Also: Google Fails Evil Test