I think there's a feeling in the NHS that BUPA - at least the hospitals - try to cream off the easy jobs.
A couple of examples.
When I had my hip replaced the consultant thought I might need a blood transfusion afterwards due to another medical problem.
That ruled out the local BUPA hospital - they can do hips but don't have the kit/infrastructure for a swift blood transfusion.
Second example is a 'bloke in the bed next to me' story, but I've no reason to disbelieve it.
He had a hip done at the BUPA hospital, was discharged, but something went wrong.
All BUPA did was tell him to go to A&E, where he was duly admitted to my ward.
His view was BUPA had made a mess of the operation, but that doesn't matter.
The point is when something did go wrong, the BUPA hospital couldn't sort it.