... So nobody should put up security cameras outside their house? That's what these are, that's it. In such a situation most people would consider security cameras a pretty good investment.

I think it's also worth considering what can happen if there aren't cameras - eye witnesses suck. What if someone (or more than one person) claims to have seen you walking by a house that got robbed, and there's no video to prove your innocence? If people are hyper-aware that crime is happening they're going to be paying extra attention, while probably still doing a very bad job of determining what's actually going on.