Richard Ashcroft at Blenheim Palace on the Thursday before although at an event only Sugababes as the headliners I believe has ever done it. But if you're getting that close and not doing it now I reckon there's no interest in what being offered from both sides.
If the field is full and she sells a heap of tickets (both near guaranteed) - then who cares.
For whatever reason she seems to go down a treat with all ages - plenty of people who often moan about popstars are a fan. Don't look at it so statistically.
There is no reason her crowd sizes won't be like these recent USA shows - its exactly the same as with Billie Eillish / Dua Lipa in recent years.