Why do many houses have No fences????

Because we live in a place where fences are not needed. If we had fences, it would block the pedestrians from walking and block the cars from parking. Without the fences, it just gives more space for people to drive on the road, park near the sidewalk, and walk by.

Maybe because security in their area is great and/or that's how they wanted to design it. If I am them also, I wouldn't like fences too in my house. But like you, I live in a place where, security is a risk (although low because the village has security guards) and thus fences are needed for extra protection.

I think because the areas around their houses are more like 'passages between their houses and the world' than 'extensions of their property.'

That's odd. Around here (Oklahoma City), the only fences houses have are 'around their back yards.' I haven't really thought about it, and I don't suppose anyone else has either; but I think it's because they're all hypnotized into being greedy treasure-gluttons who a) want to seem to be take-in the abundance G-d freely shares with the world, but b) secretly don't want to share any abundance they think is "theirs."