Being a devil's advocate for a moment, why do they respond in the first place about taking photos of kids ?
It's not illegal it's not a problem and not the police's business, it's just fuelling suspicion.
IF every complaint like this got 2 questions from the call centre?
1/ is the kid dressed ?
2/ is the kid in public ?
if answer to both is yes, then why dont the police just say "nothing wrong here, thanks" and do not respond.
When they respond then the public automatically SEE a problem.