The 'small fish' cannot afford all of the means to ensure that they can avoid detection. The 'big fish' have the best dope, the best doctors, and the most resources.
Unfortunately, doping has long been a part of the sport and will probably continue to be. There are millions of dollars at stake, huge egos, fame, glory, and all that jazz.
The good news is that doping does not take away from the aesthetic beauty of the sport. It also doesn't affect the way regular riders enjoy regular rides.
I feel truly sorry for anyone in any profession who feels they have to break rules in order to become successful or achieve their goals. These men deserve our sympathy more than they deserve our scorn.