Robin, I agree with you. A while ago it was suggested that CCTV should be introduced on the housing estate where I live. I was opposed to it, partly for the reasons you've outlined, partly because of the cost which the residents would have had to bear, and partly because I felt that the introduction of CCTV would possibly make people feel less safe on the streets, because it would give them reason to think they should be scared when previously they might well not have been. The (very) few unsavoury types that you (very) occasionally see hanging around have always been scared off by a visit from the SNT. In the end CCTV wasn't introduced, probably because of the cost (my guess).