> Are you sure Lady Gaga and other corporate pop stars own the copyright to songs they sing? I'd expect these huge team projects to have corporate copyright.

Lady Gaga almost certainly sold all of her rights to her label, a corporate entity, when she was signed. However, because of termination rights, 30 years later, that contract will lapse, reverting the rights back to the original artists. If 20 people created the Lady Gaga song, then it will revert back to all 20 of them jointly, and if a label wants to buy the rights, it will need to make deals with each one individually.