Because they are illegal to everybody other than the Fed’s?
http://www.dpl-surveillance-equipment.com/articles/article_26.html
Furthermore, to state that cell phone jammers advertised are “[f]or [e]xport [o]nly. USA customers must be authorized Law Enforcement and/or Gov. [sic] Agency approved.” Section 302(c) of the Act and Section 2.807(d) of the Rules exempt radio frequency devices intended for use by the federal government from the general prohibition on marketing of unauthorized equipment. However, there is no similar exemption allowing the marketing or sale of unauthorized radio frequency devices to state and local law enforcement agencies.
What's this "illegal" you speak of? LOLOLOLOLOLOL!!!
Did you oversleep on July 5?