Not only do they have to take pictures, the unit has a webcam which a ministry overseer can access to watch for fraud attempts or help the technician. I'm told (but don't know with any authority) that the new fine for a technician trying to scam the system is $4,000,000.
I don't know what plates have to do with anything, but they do have to scan the VIN barcode, which I'm guessing is where fraud might be committed with the current system.
Doesn't the OBD-II signal have some vehicle identifiers too, or is just no database to correlate ECUs to VINs?