Audition project just substitute one bias for another. They also presuppose that those who will actually work with the candidate are somehow more enlightened and above bias than the standard interviewers.
That seems more like a question on how the candidate's work is measured.
While there's always some bias, I think it shifts quite a bit once you move from an artificial "interview environment" to a work environment.
Plus as has been said, since they candidates are working with the people they would be working if hired and that relationship doesn't work out, then maybe it's better to keep looking for someone else.
In my experience, those who must work with people 'on trial' hate doing so. They treat the entire experience as a chore, well aware that 90% of these people won't be around next month. That lack of commitment by the organization means those in control are only more free to express bias because they know the person at issue is already disenfranchised and weak.
