The band is kind of an underexplored facet of AI.
It seems to me they have tremendous power. They can help make a mediocre performance sound great, or screw over a performance that would have been good.
This probably wouldn't fool Simon, but it's "America's" vote that counts. A messed-up tempo or a sour note or two could really submarine someone.
If I were an AI contestant, I'd be bringing the band snacks every day, finding out what kind of music they want to play, and acknowleding them after every performance.
I'm sure AI has safeguards in place to ensure that the band doesn't sandbag a contestant, but surely they can't help but want to work harder for some contestants than others, right?