I've been to a random concert out there during the week, and couldn't get service. I think the issue is that the network out there is built for a rural area, and anytime an event is held, no matter the size of attendance, it overwhelms it. So yes, for the large events, they bring in the portable solutions, but that is not likely something that happens for EVERY event.
Your comparison to downtown doesn't really hold any water, because it is an extremely high density area by design. And has the infrastructure to function as such on a daily basis. Also, downtown has been downtown for a hundred years. Elroy was Elroy until 10 years ago. Telling folks to move from an area their families have lived for likely much longer than the idea of the track seems pretty selfish. The track should be responsible to for improving the infrastructure to handle the problem they created.
Otherwise, it should have been put in an area that would not disrupt anyone.
It all comes back to the fact that ownership of the track does absolutely the bare fucking minimum, for EVERYTHING. Which is really a shame. I had so much hope those first few years for truly a fantastic experience. At this point, I'll be surprised if races are still being held there in 10 years time.