You can't, strictly speaking, prove anything, but nobody drives that close to the curb unless they are in the process of parking or are pulling away from a parking space.
We don't know for sure if the car is parked illegally or not. If some member of the entourage has a physical handicap - besides the mental one they all have - they would be able to legally park there, as long as the car had the proper sticker or license plate or placard or whatever else would be required.