My other half auditioned with her sister (who is Helen x 10 = nightmare) 4 years ago and got into the last 100.
They asked her to come back but she never has. Anyway, my point is they had 1000's of applicants at the Emirates stadium and it must have cost a lot of dosh to organize those auditions, so I think they would prefer not to have open auditions at all and just have folk send in VTs for them to short list, or, save even more dosh by scouting (which I'm told they always did, but in the old days it was more a case of them approaching people in the streets, clubs and pubs and inviting them to apply).
I guess it always comes down to money in the end.