Per-stream rates are actually similar to the per-listen equivalent for CDs, and the revenue difference is because listeners have different behavior now that music is less scarce and is a la carte.
In the CD era, artists earned more revenue because listeners had to buy whole albums, even if only a few of the tracks were worth listening to.
People also listened to fewer artists, because listening to something new was expensive.
Some napkin math:
Say a CD costs $18, the artist gets 6.6% of that, it has 12 tracks, and you listen to the whole CD 30 times while you own it. That gets you $0.0033 per track listen.
(Thinking of how I listened to CDs twenty years ago, an average of 30 listens feels like an okay estimate. Some albums more, some less.)
Gizmodo reports Spotify pays $0.003 per stream.
While there's some wiggle room in my CD calculations, I don't think they're off by e.g., 10x.