reasons: there's no motivation to cheat-- no money, no scholarships, no "next level" -- it's an athletic dead end, especially football. Teams that made the national playoffs, or individuals who made nationals in say, track or golf, were urine-tested, I never heard of anyone failing, and we had people go to nationals in track, golf, b-ball, every year. You need "pure" sports, that's your ticket. Hell, it was hard just to get guys on our team to lift weights, much less cycle 'roids. That kind of stuff can damage an investment banking career...
however,
In H.S. our middle linebacker had a 50" chest, 32" waist, 380 lb. bench press, horrible acne, and tended to pee blood before games at age 17, his kidneys were so shot. That was all the evidence I needed to keep clean. I'm sure he got his stuff from Tijuana and didn't have professional-coach type help though.
The evidence linking steroids to rare cancers is sketchy and anecdotal-- there aren't enough Alzados out there to prove Alzado's claim that steroids gave him brain cancer. The links to high cholesterol, high bp (probably from water retention&weight gain), kidney damage, and atherosclerosis are not, nor are the 2ndary sexual affects (shrunken balls, bitchtits).