John actually they couldn't do that under equity guidelines. In the first place, it is a broadway show performing under an equity contract so there isn't much room for variation in the audition procedure, second the filming aaspect had to be covered under a rider filed with Equity so all the rights of the Union performers and the jursidiction of equity and its sister unions could be preserved
The EPA was actually a preliminary audition under equity guidelines. The open call was a preliminary audition as well. Everyone had to audition first before they got to be in front of the three judges.
If you were a Danny or a Sandy type and wanted to go to the epa you still were considered for danny and sandy. If they liked you they called you back
There also is nothing stopping an equity performer from going to the open call. Although I wouldn't want to do that considering that the equity call was a lot more organized.
There were also agent submissions for this show that the Tv show doesn't talk about. I know because I saw the breakdown.
Other than that, did you enjoy the play Mrs Lincoln?