When they were casting "Hannah Montana", several young girls in Florida, including my daughter, were sent on agent calls, only to find out that they had no intentions whatsoever of casting outside of LA, and that the roles had been already cast prior to the auditions. It was for publicity and to gain attention from the right groups of people.
It's sad, but true. But, again, you never know, so it's worth going to these auditions. And, they may be looking for future projects, so you never know when you might be the right person at the right time.