It's rife in all sports
The people who supply the best and newest PED's openly tell you they are ahead of the testing and the testing is always playing catch up.
If you have the big money, you can afford these doctors and there's less chance of being caught unless your cycle has been messed up and the testers have caught up
Look at the Jamaican sprint teams, they completely dominated for a bit around the when Bolt was around. There was very little testing inside Jamaica at the time, even by the testing organisations, they didn't go there to test. So they were cycling all kinds of PED's. Their absolute dominance ended when they started getting stricter with testing over there.