Do you realise just how much better a deal 30% is compared to buying a CD from a record store? For any muso who hasn't already sold their soul/rights to a major label (and who's not in Bono's infinitely privileged and connected kind of position), iTunes sales are a fabulous deal.

You're still right though, KU is more comparable to Spotify, where songs are effectively "worthless", but artists consider it worthwhile to give away their music there for discoverability - Zöe Keating used to publish year;y blog posts as raw data as spreadsheets showing how (litte) the variou streaming services (who didn't prohibit her contractually from doing so) paid.