It could be either:
a) an ANPR capture (unlikely for a "parked in parent & child bay"), or
b) a "disappearing PCN" (where they put the PCN, but as a Parking Charge Notice, on the car, take a photo of it, but the NTD has miraculously disappeared by the time the driver gets back.
Either way, DON'T identify the driver, and if they want to reply on 'keeper liability', they are scuppered anyhow.
Don't touch them owe me £500 since January 2019 make excuse after excuse. Seem they always have software problems sending money out. Keep saying they will call back or email nothing been chasing it now for 6 mths the phone staff always have the same banter we will chase it up and get back to you then nothing!