Even in that case, every athlete has nearly the same conditions. Yes, over the course of a day, those conditions can change, but the organizers can control for that as best as possible. In your snow sport example:

> "The start order in the first run is determined by a combination of a draw and your standing in World Cup rankings. For the second, the top 30 skiers start in reverse order (so the 30th person goes first) to even out their chances. The later on you start, the worse your course conditions will be, sometimes with gnarly ruts, holes and bumps." [1]

While yes, a better athlete would start later, and therefore be at a disadvantage, it evens out the field so that they can close the gap in the effects of the course conditions.

[1]: https://qz.com/1202352/a-short-guide-to-understanding-alpine...