Apple Music has a feature based on iTunes Match that will take your local files and attempt to match them based on their metadata and audio fingerprint.

The last time I used it, from my (then) ~5000 song library, it matched ~3600. That means that a good third of the music I listen to is not available in the same exact version on streaming services.

I dug into why, and reasons include:

- The LPs were never licensed properly. Such as Exmilitary by Death Grips, which is a bootleg release with copyright issues.

- The artist hasn't signed up for streaming, like it used to be the case with Tool. Or they only stream on one platform and not another. Dr. Dre and Jay-Z come to mind. All three artists I mentioned in this bullet are "really mainstream."

- The version I like is not the streaming release. I like the casette version of Ashes 2 Ashes, Dust 2 Dust by Tommy Wright III, but not the CD reissue.

- The artist is actually too niche. I have quite a few things in my collection from Bandcamp or Soundcloud that don't exist elsewhere.

- The release is "weird." Like the radio stations from the classic GTA games.