It seems weird that we live in a boom time for testing, but we do. The science of testing was mostly perfected in the middle of the 20th Century and not much has changed since then. It would seem like it ought to be a sleepy business. Moreover, very few people defend testing in public. Yet the media climate keeps pressing the vast education system toward policies requiring ever more new and improved tests and test prep materials. Commenter gb at The American Scene says:

New York State's entire "Race to the Top" grant will be used to pay for assessment tools, and the testing companies are in it for the money in a way that teachers certainly aren't. Kaplan, which owns the Washington Post Company, owns the very lucrative contract to provide test prep materials for the New York City schools, and Joel Klein, great champion of testing, has just moved from the Chancellor of the city schools to the News Corporation, where he will work in educational publishing. In many ways, assessment is a mechanism whereby federal, state, and city education dollars get moved to large media conglomerates-meanwhile arts education and foreign language instruction get cut.

When you stop to think about we really have the perfect intellectual climate for well-placed firms to make money off testing: when your tests don't give the right results (perfect equality), then your writers demand both more tests and new tests. And nobody is allowed to point out in your pages that it's all pretty futile. It's a perpetual motion money-making machine.