According to all guides online, all races in Mario Kart Tour (for the time being) take place against AI opponents. This makes sense because I am always able to skip the little "panning view around the course while music plays" part when a race starts, which wouldn't be the case unless all players did so at the start of every race.
However I was very surprised upon first learning this, because when waiting for a race to start, it definitely seems like I am being matched against other, real-life players. Some of the opponents have usernames that are in Japanese, others in English. And if these are just faceless CPU racers, why would Nintendo be auto-generating names like "pablo_damn" and "aaathebest"? Plus on top of that I have been getting opponents that have badges associated with their profiles, while others don't have them. And adding even more confusion is the fact that sometimes it will take a large number of seconds to find other players to race against, while other times it is near-instantaneous matching.
Yet I know these can't just be ghost-racers of other players' times, because then they wouldn't be able to react to my actions during the race in real-time. So what's going on?? Who am I racing against in Mario Kart Tour races? Is it real players? CPU-controlled robots? Some strange amalgamation of both?