Design wise, it looks awfully similar. Sure, it's because both are based on old style arabian towns, but they do seem very much like each other. Compare:
Mario Kart 7 Bazaar
Wario Land 4 Arabian Night
Hard to see, but if you added some clouds in the sky of the Mario Kart 7 one and changed the palette of the moon, they'd look pretty similar in general style. What do you think?
Even so, seems cool that Shy Guy is not only playable, but even gets his own track! I am deliberately trying to not watch any videos of the tracks, since I want to experience them for myself when I get the game. Screenshots are fine though, they don't show the layout of the track. I mainly use them to spot what the background will look like, the kind of track we'll be racing on (dirt, road, ice, etc.) and of course for anything that may resemble playable characters.
Shy Guy? Own course? Darn I hope this is awesome to race on. It looks awesome anyways! And the resemblance is pretty close too, interesting find, heh. I'm sure there will be heaps of other courses with odd similarities, no doubt.