It's set up so all contestants get the exact same set of mods. Finishing in world record time in such a competition is indeed meaningless; it's just about winning the race.
So this isn't necessarily what you'd call a randomiser — often the mods aren't randomly generated at all, but carefully curated by the event organisers. But it's à propos in terms of 'new experience every time'.
One neat aspect of this approach is how unexpected the mods can get; e.g. your player character could be swapped out for a character from a different game. Then there's the extreme variant of mystery races, where the runners don't even know which games they're going to play.
So this isn't necessarily what you'd call a randomiser — often the mods aren't randomly generated at all, but carefully curated by the event organisers. But it's à propos in terms of 'new experience every time'.
One neat aspect of this approach is how unexpected the mods can get; e.g. your player character could be swapped out for a character from a different game. Then there's the extreme variant of mystery races, where the runners don't even know which games they're going to play.