Despite the reach of global communication, there's a good chance those people never find out that others are searching for this info. They may not even be alive anymore.
A year or two ago, some friends and I had the theme of "rare or weird songs" for a monthly "bring your own music" listening party. Since the previous theme was "songs from your childhood/youth" and I like to throw in a bridge to the previous theme when possible, I brought in the recording of a practice session I did with a band back in college around 2000.
I'd since digitized the cassette tape and probably have the only copy of this recording in existence. The band played one show and it was generally just a fun project among friends. We never recorded a proper album, only set up a tape recorder during one practice session as we ran through the whole set.
There must be hundreds of thousands of similar recordings out there from bedroom projects and bands-that-never-were.
One of those tracks was "Cry Little Sister", which was drawn from the Lost Boys soundtrack, and definitely was never performed by the Sisters of Mercy, despite what all the ID3 tags said. https://en.wikipedia.org/wiki/Cry_Little_Sister
I remember (a friend) downloading Box Car Racer's new album on p2p only to find an indie band had uploaded their own songs under the legitimate BCR track listing. While immediately clear they weren't BCR, friend was intrigued and continued to listen to them for years without having any idea who they really were.
Some friends had some songs almost 20 years ago that was actually played in the radio by a DJ friend of ours. It wasn't any good, but I reached out to the four of them and asked if they still have it. Nope, the four of them have no idea where the songs are.