> A megastar can choose to record any of dozens of equally good songs. Whoever they choose will sell 100x more. So in one sense it's fair they get a share of the money they create by adding their fame and talent to the song.
I don't think this is actually true, at least if you define "good" as "likely to be a hit". There's a reason top pop performers go for songs written by songwriters with a proven track record, the most famous of which is perhaps Max Martin. Not anyone can write (and produce) songs that consistently appeal to whatever the public preferences of the day are. And no one wants to take unnecessary risks.
I don't think this is actually true, at least if you define "good" as "likely to be a hit". There's a reason top pop performers go for songs written by songwriters with a proven track record, the most famous of which is perhaps Max Martin. Not anyone can write (and produce) songs that consistently appeal to whatever the public preferences of the day are. And no one wants to take unnecessary risks.