How could that ever be distributed fairly? How do you determine what percentage the Gaga's get versus the indy artist down the street? Given this would cannibalize sales, you wouldn't be able to use sales figures because there would be no way for a new group to get to the level of sales a Lady Gaga had.

If the government starts deciding, you make music a communistic business, which would not be good for music.

(For the record, I think the levies as they stand are wrong for the exact same reasons; you just replace the govt with groups like the RIAA.)