Theory: Tour Earth is Smaller than Earth

Abstract
Tour Earth is considerably smaller than Earth.

Arguments

 * Argument 1: The cities we see in Mario Kart Tour seem to be much smaller versions of real cities, with landmarks being much closer to each other, and with buildings and streets generally being smaller, implying there was less land to build upon.


 * Argument 2: Mountains, such as the San Gabriel Mountains, and rivers the Seine River, are much smaller in size compared to their real-life counterparts, suggesting the planet is also smaller.


 * Argument 3: Uluru can be seen from Sydney on Tour Earth when it's very far from Sydney on Earth, indicating a massive difference in distance between the two on either version of Earth.