
This is because are no teams in track, and of course no natural rivalries like Yankees-Red Sox, Dodgers-Giants or even Bears-Packers. We don't exactly get to see the Bay Area Track Club take on the Oregon Track Club in a raucous arena with partisanship split based on regional ties.
In the place of this lack of local regionalism is a general support for every runner competing for your country. The Olympics and World Championships draw on this and bolster this concept by having athletes be both representatives of their countries (wearing their nation's colors) and subject to the selection processes of them too.