In the UK? It depends. Any children anywhere around and he'd be in for a hard time. Unlucky with the police officers he got? He'd be in for a hard time. Not great with the answers he gives? He'd be in for a hard time.
Photography in public is one of those topics that opens the door to armchair lawyers. People who have no training and little knowledge who just make stuff up off the top of their heads.
Interestingly in the UK there are specific exemptions for journalists. I'm not sure how tightly defined journalists are; there are press badges and journalistic qualifications, but that feels like a little bit of law that hasn't caught up with the Internet.