probably because of Money
I looked up steroid and the law and there is a small group trying to change the law and make them legal here is a quote c&p
Movement for decriminalization
After the Anabolic Steroid Control Act of 1990 listed anabolic steroids as Schedule III controlled substances in the U.S., a small movement has arisen that is highly critical of current laws concerning anabolic steroids. On June 21, 2005, Real Sports aired a segment discussing the legality and prohibition of anabolic steroids in America.[105] The show featured Gary I. Wadler, M.D., chairman of the U.S. Anti-Doping Agency and a prominent anti-steroid activist. When pressed for scientific evidence by correspondent Armen Keteyian that anabolic steroids are as "highly fatal" as is often claimed, Wadler admitted there was no evidence. Bryant Gumbel concluded the "hoopla" concerning the dangers of anabolic steroids in the media was "all smoke and no fire".[105] The show also featured John Romano, a pro-steroid activist who writes "The Romano Factor", a pro-steroid column for bodybuilding magazine Muscular Development.
interesting.