Because this is clearly the fault of teachers unions and low expectations (boldface mine):

In November 2013 the Texas State Board of Education adopted new science standards for its textbooks that will bring evolution into the Texas public school classroom…

Neil Frey, acting on behalf of ERA, has been aggressively lobbying since the decision to change much of the wording in the textbooks. Frey’s complaint, filed with the Texas Education Agency (TEA) alleges that Pearson Education’s high school biology textbook is wrong in explaining the close similarities between chimpanzee and human DNA. The textbook states that scientific evidence shows that chimpanzees are the closest living genetic relatives of humans.

Chimpanzees are in fact the closest living relative to humans, but creationists do not like that, so they file complaints. Pearson responded to these claims, disputing Frey’s complaints, stating that making these changes would be misleading to students’ education.

Now Frey has convinced an SBOE board member, Barbara Cargill, that his claims are valid. This comes as no real surprise as Cargill was a board member who opposed the standards change from the beginning.

It continues with an episode of creationist lying–I know, you’re shocked. But education reformers never criticize these efforts to introduce nonsense into the science curriculum. Teachers, especially those who can’t be fired without due process (‘tenured’), on the other hand, do actively oppose the dumbing down of the science curriculum.

Maybe the problem is our low expectations of education reformers?