The ubiquitous security cameras strike some people as sinister, but I think they do a lot of good, for a tiny price in "invasion" of our privacy.
But I'm not as hard on Perry as many here. It's possible the girl had mentioned some of the social services contacts to him, leading him to think things were already being looked into. And he said Nixzmary ran to her mother, as soon as her mother appeared. Was Perry supposed to stop her? And what good would it really have done if he HAD taken some action? There had already been multiple social service and law enforcement contacts with this family, in one case including a doctor who examined her, sewed up a gash on her head, and told authorities he saw no evidence of abuse! The supervisor at the child welfare agency who was assigned to Nixzmary's case had resigned recently -- formallly just a few days ago, but he hadn't been in to work since Dec. 9, when he was discovered to have altered his files to cover up his ineptitude in the case of ANOTHER child who was killed a few months ago. Frankly, I think the chances that Perry's putting in a call would have resulted in a different outcome are slim, and as someone who lives in that neighborhood where a lot of this sort of stuff goes on, he's probably all too familiar with how useless the authorities are in carrying out effective interventions.
How would people have reacted if a 49 year old single man grabbed the little girl and carried her away from her stepfather to a police station? He probably didn't feel like there was much he could actively do, but he could have called child protective services.