Check out this article from NPR– the answer to the question of Section 508 enforcement is a sad story of inaction:
It has been 10 years since the Department of Justice filed a biennial report on the federal government’s compliance with accessibility standards for information technology, a bipartisan group of concerned senators say. The reports are required by Section 508 of the Rehabilitation Act.
“To have no reporting in a decade is just … unacceptable,” said one of the senators, Bob Casey, D-Pa., told NPR.
“It’s critical because of the barriers that people with disabilities face all the time, when it comes to the full access that they should to have the resources of the federal government, and the resources, especially that are provided online,” he said.