To be fair, I don't think Flock is focused on one/two camera neighborhoods. Around here, they seems to be cutting deals with cities for a few dozen cameras at a time. It makes sense. The cost of selling/supporting this is much lower. Plus, Flock's "technology" (solar power, cellular connectivity, ALPR/AI/aggregated database) seems to have much greater value for this scenario than a neighborhood where power/connectivity is easily available and the main requirement is plate capture.
I do think there is a biz opportunity for neighborhood surveillance. I don't know about selling a system, but configuring cameras optimally (acceptably?) requires a lot of knowledge/experience. It seems like there should be a market for a service that you could email in videos and get suggestions on tuning (kind of what you do for free on IPCT).