Let me preface what I am about to say by letting you all know that I am a male victim of sexual abuse.
I do NOT think that letting the government spy on people without a warrant is ever a good idea. Sure, there are internet pedophiles out there who look at pictures of young children being molested. The sad fact of the matter is that trusted authority figures are far more likely to be doing the molesting and picture taking. Babysitters, coaches, doctors, uncles, aunts, older siblings, clergy, are all far more likely to molest a child that some predator driving by and snatching a kid from the playground.
As far as the comment about "people just know." When I was in middle school people just "knew" I was gay. I got beat up, harassed, threatened, and in one case my head put a dent in a locker because people "knew" I was gay. Fun fact: I am not gay, or even bisexual. Now let me see if I can imagine that people "know" I am a pedophile. Cops look the other way, eventual I would come to bodily harm, perhaps even be accused openly of molesting a child. Perhaps even be accused by a child (3% of reported sexual abuse cases are wrongful convictions).
The poster seemed to give omniscient knowledge to a community.
Back to privacy: I don't want someone looking in my window. You might be different(different strokes for different folks). I especially dont want a cop looking in my window. I don't even want a cop to be behind my car, not because I am doing something wrong or plan to, because I don't like being watched.