Basically there's the have and have nots in the sport. Roush, Hendrick, Childress, Gibbs and Penske.
And then there is everyone else. And the gap between have and have nots is getting bigger (very baseball like).
So a lot of the smaller have not teams have folded or downsized(Red Bull, Petty went from 3 or 4 cars down to 2, Ganassi is down to 2 etc). Well when they do that, these small timers go and buy their cars and run them out there and collect purse money. Most of the start and park guys are running cars that are 1-2 years old. Even if they wanted to run the entire race, they would be so uncompetitive it would make no financial sense to spend the money on tires.
How to fix it? I doubt they can anytime soon. The little guys don't have the bucks to upgrade and try to run with the big boys, and those same big boys also dominate the Nationwide races (Sadler drives for Childress, last year's champion is in a Roush car etc).