Britney Britney is a prop. She doesn't write her own songs. She can't sing her songs (as proven by this video). She doesn't really interact with her fans (see below). She lipsyncs at her concerts.
She's just a sponge to soak up popularity, fame, and riches while the hardworking people behind her talent get much less.
That's the tragedy of it all. She shouldn't get so much money for doing a disproportionate amount of the work.
This is just another unfortunate drop in the bucket, unfortunately. I don't know exactly how many of the major pop divas are also props, but something tells me it's the majority. Especially once they rise to super-stardom and their focus drifts to sensationalism and building their brand.
Is she a robot? Only the executives at Sony Music Entertainment know for sure.