Antony from Blue tells an amazing story about this.
When they were successful they pushed to write their own material. The label pointed out that the songwriters they had were in the business for 30 years, had produced hundreds of hits, and writing a hit song is incredibly hard.
The compromise made was that they were allowed to sit in on songwriting sessions and get a credit if they made a contribution. So hes named as a co writer on an album track for saying “what if we change that ‘the’ to an ‘a’
A lot of label earners get the ego boost of sitting in on writing sessions, but even as talented a songwriter as Gary Barlow has had a tiny amount of success writing for others. Pinnock is listed as a co writer on one 2015 Britney track on Wikipedia and the rest seems to be “yeah they can co write the album tracks but not the singles”
I’d love to see a breakdown of their tour profits though - must be impossible putting on a suitably flashing show in the mid size venues they play but keeping the ticket prices low because it’s purely a mums and kids audience and they won’t pay over the top cash for tickets