Legal Physical Enhancers/Steroids

[RocketManJames]

Let me preface this by saying that I don't know anything about this subject...

I am sure there exist steroids or physical enhancers that are legal, but banned from competitions/events.

Why don't they just have different categories for individual events, like running? They could have an Open category and a No Banned Substances category. There are lots of competitions that have categories, not limited to physical competitions...

In chess, there are open categories and some that are limited by official ratings.

In junior tennis, there are categories for different age groups.

In fingerprint algorithm competitions, there are categories for open (no memory constraints) and light (speed and memory constrained).

So, why not have these for major competitions as well?

-RMJ