I used to work with a girl who's boyfriends job was to buy fruit and veg for supermarkets.
She said the only difference between cheaper supermarkets are more expensive ones was the more expensive ones charter aircraft to deliver their produce, whereas cheaper markets produce came by boat.
Meaning, the more expensive stuff should last 3-4 days longer than the cheaper stuff.
I know anecdotally we'll all have instances where that isn't true, but then that would be an issue with that markets management not selling that produce quick enough, so the older stuff lingers around longer than it otherwise would.
She said the suppliers would largely be the same, maybe the more expensive shops get first pick of the produce? Not sure.
But it was interesting all the same.