I read somewhere that the Army & law enforcement recruits who make the best marksmanship students are the ones who have no civilian firearms experience. They have no bad habits to unlearn, What if proximity and familiarity to Aes Sedai results in a mindset among the recruits that makes them more likely to fail one of their tests? The Aes Sedai are always going on about how a clean break is best for the recruits, but how possible is that for girls who see their families every holiday and day off? For a girl off the farm or another city, Tar Valon and the Tower are a whole new world and an alien environment. There is nothing familiar to cling to, so they start as blank slates for the Tower. That ritual burning of the clothes they wear to Tar Valon is part of that practice, as is the curtailment of sexual or romantic relationships with outsiders, despite letting them indulge with one another to their hearts' content. You can't do that with a Tar Valon native, for whom the White Tower is not so much a thing of legend as a local landmark. And while the sisters certainly don't let the local girls get away with backtalk or anything and do their best to root out attitudes of complacency, it's like Moiraine's talk with Rand about the first impression of a ruler, how if they first see him as a commoner, no matter how they intellectually accept his abstract right to rule, they will never really shake that first impression, and likewise if he makes a regal first impression, his subsequent commoner behavior won't totally erase that. And that's just a first impression. For a Tar Valon born novice, her first impression of the White Tower is going to be sixteen years or so in the making.

What's more, Tar Valon girls would probably be more familiar with the courtesies and honors due a sister, and would superficially need less correction. The knowledge that she is from Tar Valon might also subconsciously have the sisters thinking of her as one of theirs, and thus the attitude would go uncorrected.

I always come back to the bit with Moiraine and Siuan in New Spring with the ink spill, where Moiraine figures out that she is being given tacit permission to clean it with the Power, while the more rebellious Siuan is shocked at her breach of the rules. Siuan almost certainly had obedience beaten and trained into her, while Moiraine required less corrective attention and went a lot further toward voluntarily accepting the rules of her own free will. Thus, she can more easily choose to set them aside when they are no longer suited, as in the case of a woman on the verge of the shawl. Siuan has been conditioned to associate pain with violation of the rules, and her supposedly keener mind for intrigue and more rebellious nature completely fails to notice the implicit pass they were offered.

I think maybe Tar Valon girls, for whom the Tower and Aes Sedai are much less of a mystery and who are not so awed or impressed as village girls or natives of lesser cities (who probably fare no better at the sight of the Ogier structures and the rather unique Tower), in some ways have that same voluntary acceptance that Moiraine had of some aspect of the training or indoctrination. Just as the MoN & teachers saw Moiraine's better behavior and did not feel the need to beat obedience into her as they did Siuan, so the sisters in charge of the various novice groups which include Tar Valon natives don't see the need to impose this mentality on the local students, because they give enough of a reasonable facsimile of the outward behavior. And so, to them, that hypothetical necessary attitude is no more than a hollow courtesy, instead of something they desperately need to keep in mind to keep their assess unblistered.

I think that paramount acceptance of the Tower as the be-all and the end-all, that near-worship of the Aes Sedai as an institution, which holds the Tower together in spite of Ajah rivalries and clashing personal ambitions, is what gets lost on the local girls. They already have a concept of the Tower, whereas the outlanders are a tabula rasa on which the Aes Sedai can write the image they wish. The Tar Valoners say and do all the right things when they get there, but maybe they don't have the respect or awe or devotion in their bones and never come out of the arches, or say "screw this for a game of bullshit" and refuse to go in.

Another thought had to do with the possibility of resonances triggering early manifestations as if they were tested, and then killing them, but I think that'd be noticed.