Most reality TV, even if its billed as a "contest", is first and foremost a TV Show, so the viewer should never expect all contestants to get fair shake. The producers have the important remit to make a "show" leading to a certain conclusion that is tempered by the popular vote but they also have the power to de-popularise any contestant they want, all in the interest of providing good TV.
If the producers do not know the "ending" of a story, how can they create the episodes that lead to the final. Of course, the "team" of judges and ALW conspire to promote certain outcomes, after all they are trying to will the audience to select the one person they themselves have auditioned for the part.
Dress, music, song choice, lighting and camera work are all utilised to boost or spoil a performers image on the small screen to achieve this end. Its never been a fair contest and nor was Maria or Joseph and the very idea that "Any dream will do" was quickly replaced by "so long as its the dream I want you to have". Avoiding the obvious, such as forced song choices that are then criticised, would be a good idea but the public very often do not notice these contradictions.
When the Auditions were completed, ALW and his team then set about building a final 12 around the one they selected for the part. The whole idea is that it seems like a "contest" and not a walk-over. To do this they include "hated" characters, great singers unsuitable to the part and then point them out to us every week in the full knowledge that the gullable public will send them on their way. Great singers and actors (who may have compromised their "selected" player) are dispatched to the cutting room floor and people like Nancy Nancy don't get a part in the "show".
Maybe I am just an old cynic, or maybe I have seen too much reality tv, but we, as dutiful public, always deliver "the required result".