You missed where they paid him while he still was in the dealership, i assume. That must’ve been a rather speedy check, without any pictures etc.
While you’re not incorrect that the decision ultimately is by MB, they don’t hand check every application – they got a sheet and mark the wear and tear in different categories. If nothing’s marked by the dealer in the (lets call it) “red category”, the GCB gets automatically approved.
It’s their job (and responsibility) to check the car, so technically it is their decision. If they give the green light, MB pays.
Prior: SEAT Ateca Xcellence Lux 1.5 TSI DSG MY19, VW Golf GTE PHEV DSG MY23
Current: Hyundai Ioniq 6 Ultimate
Next: we'll see what's available in 2028.