On Reading Safescape

I'm reading "Safescape", by Al Zelinka and Dean Brennan.
Nobody wants to be unsafe.
However...
And this is a big "however" because I moved to rural Maine partly so my children would be growing up in a safe environment:
Is there a difference between "safe" and "good" design? Which begs the question, what do we mean by good design?
There is a time when the community is so strong, and the impacts of humanity so small, that no design is necessary to have a safe, healthy environment. That is probably what rural living is all about. It's not just that the houses are far apart. It's that people have a surplus of freedom, so their natural inclination is to be friendly in public. There are so few people, you have to be nice to strangers.
When populations get dense, trouble brews, and you have to be more careful. You have to design your physical environment to minimize opportunities for trouble. When does a community cross that line? When do they know they have crossed the line? Is there a way to go back?