Types of songs that are hard to find are by artists who do not offer their music on streaming services. For example, as of 2016, Taylor Swift does not offer any of her hit songs, such as "Blank Space," "Style" or "Out of the Woods," on the streaming service Spotify.
Prince does not have his songs available on any streaming service, except for TIDAL. Some other artists that don't make their songs available on streaming services include Thom Yorke, Garth Brooks and Tool, because they believe fans should listen to their music in the context of an album. Bob Seger also doesn't have any songs available on streaming services.