Then how do you explain the olympic games? Tour the france? Just to name a few..
The drug tests work.
They are getting caught.
Right now, more than 100 athletes are banned from track and field internationally.
You cannot detect EPO unless the person was injecting it just hours before the test. And they likely won't be that stupid.
But several sports federations, among them the IAAF (Track and field) UCI(cycling) and FIS (cross-country skiing) have implented blood level registrations for their athletes.
Which means that if the hematocrit level of an athlete is juiced up (from EPO use) the test will easily show this.
The problem is really in getting the tests done.
How are you gonna be able to find a Chinese track athlete when there are 1 billion Chinese people who looks the same?
(j/k DK).
Seriously though, the hard part is to find the athletes, to get the out of competition tests done. Some people train in a little village 1000 miles outside Moscow. How easy is that to find?
Some countries are getting serious about it. Like Germany and Hungary, and also up in Scandinavia. Also UK tests pretty hard. In both Hungary and Germany, it's illegal to test positive, you risk jail time.
Which is probably why Hungarian discus thrower Robert Fazekas avoided getting tested in Athens - he didn't want to end up in Hungarian prison.
But you have to wonder why some sports, like football, never have any busts. With the Champions League, Premier League, FA Cup, Worthington Cup and tons of friendlies, the footballers have an extremely hard schedule.