Mario Kart World upends the series in several ways (not the least of which in price), but the biggest change is that the game now takes place in an open world, one that you can roam around freely, and even the main tracks in the Grand Prix are supplemented by races that travel between them.
One consequence of the game world is that the NPCs that inhabit it have a bit more of a life than in past games. In N64 Toad’s Turnpike, they’re just boxes that travel around the loop getting in the racers’ way. But now, when you’re exploring in Free Roam, you can pick out a specific driver and follow them around.
And what do you know, there actually seems to be a bit of an inner life going on there! They don’t seem to pathfind between locations, sadly, but they can get the mad yen to drive off the road and tear across the desert. And, surprisingly, a drive can get out of their car, which is more than the player racers in the game can do!
OnADock, on Youtube, made a 14 minute video where he followed a Toad around on their travels through the Mario Kart World, um, world. Maybe it’ll inspire you to do some investigation of your own?