when the blonde girl heard the guy telling his uncle about the song he heard, then she stole the book from mitchie. i thought she was gonna sing the song to make him think it was her he heard. but she didnt.
If she did sing it to Shane it would have been a different voice. But I think they could do more with the story then if she sang it. (bracelet stolen, no final jam etc.)
I thought it was really stupid that she didn't try to trick him. What was the point of filming her finding and reading her music journal, right after hearing that Shane was needing to find that girl, if she wasn't going to do that? I don't know, it just added to the appearance that this movie was not thought out and thrown together as fast as possible to make money.
She would have felt that she didn't need to sing the song. She was adamant that she would win and get to sing with him anyway. She felt that Mitchie was her only competetion to winning and had to stop her singing, especially as she knew that Shane was looking for her. She couldn't have sang the song anyway, as soon as Mitchie heard her she would have complained and the other two girls knew that the song was Mitchie's too.
It wouldn't have made sense of Tess sang the song.
Shane was looking for the girl with "the voice"; it was a specific voice he was looking for and Tess' voice wouldn't have matched. This isn't like "The Little Mermaid" where the evil witch could change her voice magically.
That entire sequence made absolutely no sense and it was rather pointless.
Also, did anyone find it strange Tess was "crushing" on Shane Gray and she never spoke to him. She was however always stalking him.