This. A lot of professional sports, from baseball to wrestling, have systemic doping...the difference is cycling has clamped down on it, where many others still turn a blind eye. When they look, they'll find it as well.
Soccer? Rugby? Tennis? Golf? Yachting? I don't think it's as wide-spread as you think.
Maybe some sports that require actual skill need drugs less, since drugs don't really help. In sports where it is simple endurance or strength then it does.
Funny thing is that I find those strength/endurance type sports the least entertaining to watch.
The GP said "a lot" of professional sports, not all. You list a few, that does not invalidate his point.
Having said that, the sports you listed are BAD examples. They are not the ones "turning a blind eye" because they are under the same anti-doping initiatives as cycling etc. The examples the OP mentions are sports not signed up to the world anti-doping authority. Those include (AFAIK) baseball, wrestling, ufc, ...
Even then there are still people who cheat when they think they can get away with it. Take tennis. It was only a couple weeks ago that Sharipova got banned because she had been cheating for years, but the code only caught up to ban her drug of choice recently.
Weightlifting and track and field are another 2 sports like cycling - systemic doping that they are trying hard to stamp out. The result is Russia is not even going to the Olympics because of it!!!