No real reason to feel frustrated in regards to missing this type of casting. Although this film will require many actors with talent, big casting nets like this are typically for publicity for the film. They are looking high and low for the right talent, however, they have been casting for months in both LA and NY with callbacks already taking place. Due to content matter, they are also looking at 18 plus to play younger.
It is not unusual for films to do major open casting calls across the nation. But, it is to gain attention to the film prior to opening AND to get a big audience when it opens due to prior awareness. It even gets free TV publicity. Will some people get picked up as day players or background from these open auditions -- probably. Will they get cast as leads -- probably not (if you look at trends in filmmaking).
And I definately agree on the price of camps etc. Unfortunately, showbiz is typically a "rich man's sport." We don't live in a major market and must buy last minute plane tickets for every audition/callback. It requires major financial sacrifices from our family. Also means no extra spending money left over for "training" in places like theatre camp or even with teachers in major markets. Luckily, DD has had a chance to book some nice professional roles and use those as her training. But no getting around the fact that $$ can go along way to promoting the talent.