i’d imagine that in reality a tiny minority of the potential greats actually ever see a track, for example.
Not necessarily. A good portion of the world’s kids go to schools with structured sporting programmes, so there’s a fair old chance of being noticed or discovering your own aptitude.
There’s more chance however of someone with the ideal physical attributes not having the appropriate commitment and desire to achieve. The mental attributes might even be rarer than the physical ones. Lynford Christie said in an interview that he was not the fastest kid in his school, but he was the fastest one with the required dedication. And of course the problem with sprinting is that it’s a pretty single-minded sport. Something like football or rugby is actually pretty enjoyable, so it’s likely to appeal to more kids I reckon. Running fast is very much a purist activity.
There are of course likely to be superb sprinters running around the jungles or plains of somewhere remote, but even then people are still found. Once it was discovered that people from a certain part of East Africa were great at distance running, talent scouts went there and distance running became popular. Their distance runners are big stars so you have a lot of kids wanting to be them.