[beloch]

Some music is a lot like abandoned video games. It can sometimes be tricky to figure out who owns the rights and, even having done that, more difficult still to track them down and get their permission. Also, it's not a given that the answer will be, "Yes.". If you ask an obscure artist to fill out forms and jump through hoops for 6 cents in streaming royalties, they may tell you to piss off.

There are likely many albums that would have met oblivion were it not for piracy.

[bobdvb]

There was a black and white fantasy TV show called "Adam Adamant Lives!" from the 60s. The BBC always wanted to re-release it but the original contracts for the show were written when no one ever considered re-runs and physical releases. The BBC didn't have rights from the original actors for anything other than the original broadcast. And one of the actors who appeared in a few episodes didn't want it to be shown again, even if they were paid, the BBC didn't want to release a box-set without all the episodes. Eventually they just waited until that actor died and they were then able to release it.

I'm lead to believe that in music there are some similar contractual issues. The rights for some artists were for radio, and physical media, but no one considered streaming or downloads because those things didn't exist. So they have to go back and tidy up the contracts to cover their asses. And it doesn't just have to be the headliner on the recording, you may need to get every performer/contributor.

[qingcharles]

This is where YouTube Music really shines, in a way. It lets every Tom, Dick & Harry upload whatever-the-hell, and as long as it doesn't ping off the major labels' copyright signatures then it stays and YouTube (supposedly) does some accounting around the back to try and figure out where the royalties should go.