There's actually a big community of kart players in the game and the top 10s are actually really close (think of players like Bob, LordNate, Ando, LSAN etc...). I'm a kart player who TTs regularly and yes, the competitive scene is smaller than bike TTing, but it is still there.
It's simple - he's going so fast the other players didn't have time to spawn in before he won the race. This is actually super slowed down, so us mortals could witness the godlike abilities this man possesses. That's why he can dodge all the piranha plants - he's in ultra instinct mode.
just for reference the WR on this course is now 1 minute 41 seconds and was set in 2020 so to think this is 8 years old and only 5 seconds slower is crazy
