I can see what she means.
Britney's vocal range is not the greatest .... but If you go and try to sing a song of Britney, maybe you can sing it, but it won't sound good , some of her songs are really hard to sing
"Me against the music", "Gimme More", "Everytime", "Circus", "Toxic", "Overprotected", "Hold it against me", "Stronger".... etc , etc those are really hard to sing, and those who can sing it well are not able to top Britney's versions.
Probably "I'm not a girl not yet a woman" is her easiest song to sing, because despite good vocals, it features a more conventional singing.
