Why did Clare Torry sue Pink Floyd?

Clare Torry sued Pink Floyd in 2004 over her vocal performance on "The Great Gig in the Sky", a track from their 1973 album "The Dark Side of the Moon".

Torry, a session singer, was hired to provide improvised vocals for the song and was paid a flat session fee of around £30 at the time - the equivalent of £400 in 2022. However, she later argued that her soaring, wordless vocal melody was a form of co-composition, not just a performance. As she had not been credited as a songwriter, she had not received any royalties from the track, despite its massive success.

The case was settled out of court in 2005, with Torry officially recognised as a co-writer alongside Richard Wright. This decision ensured that she would receive future royalties from the song.

https://en.wikipedia.org/wiki/Clare_Torry#Lawsuit

https://en.wikipedia.org/wiki/The_Great_Gig_in_the_Sky#Lawsuit

https://www.brain-damage.co.uk/archive/clare-torry-wins-settlement-against-pink-floyd.html

I forgot to add a link to Clare Torry's vocal part, sorry. Here it is.

https://www.youtube.com/watch?v=NAcDOpd0Lv0