I feel like people that are going to her shows, are well aware that she doesn't really sing live. You buy your ticket for the show and the "Britney Experience"
"With the help of virtual soundcheck and snapshots I'm able to recall sequenced tracks that are a very big part of a show like this, especially a dance show," he says. "Britney sings every song live, but there are additional tracks when they're doing the heavy dance numbers. Snapshots give Marc the security of knowing that these levels that they work on so hard translate to the live environment."
This is why Britney's artistic quality has declined over the years, because she had YES people covering up her crap and that is why she hasn't professed.
Plus the world knows she doesn't sing live, why hide it at this point?