I hate to explain it to a Britney fan, but... Beyonce can actually sing. Very well in that. And she never just lipsyncs, she prerecords her performances and sings over them while at the same time delivering more energetic performances than Britney. So yeah, thats why she gets away with it while Britney is (rightfully) mocked for her bad lipsyncing (even tho Im really happy to see she's doing so much better now

).