The ultimate decision is with GFL, of course, but there's definitely cases where the vendor negotiates for a specific pitch or where a local area manager wants a specific vendor. So "no say" is overstating it slightly.
I assume it varies quite a bit by vendor as well based on what they bring to the table - for example I'm pretty confident in saying that the Tiny Tea Tent would be consulted over any intention to move them - whereas the pizza stall next door may not.
Really curious about the Little Simz show. She does have the skill and energy to smash it though.
A couple of years back people were saying that in a fair world Little Simz should be headlining the pyramid and that felt like a really crazy fever dream idea. But now she's subbing that stage, I do hope one day she'll get the shot.