Keeping things off the market

Midway’s Spy Hunter from 2001 features a music video and theme song performed by a band named Saliva.
Looking through all of their albums, I don’t see any reference to that music anywhere, although Saliva has released several albums.
So, I presume that Midway has retained the rights to both the music and the video, and has refrained from releasing them, or allowing the band to do so. I also presume Midway thinks that it would not be profitable to release said music or allow the band to do so. It also seems there are tons of things that no one can find anywhere (legally) so they go to file sharing places to download them.
Does any one have the Straight Dope as to the reasons things like this fall through the cracks.
Since the production and release are already paid for on the game itself, would it really hurt to allow the release of the music separately?

WAG: Wikipedia says it was an arrangement of the theme to Peter Gunn. In which case, I suspect the rights might be in some sort of complicated legal limbo between Midway, Saliva, Henry Mancini and ABC and the powers that be have decided its not worth paying the lawyers the cost it would take to sort it out.