This is a valid point. Also, the city isn't really populated by very... rational people.

There's a city north of Portland called Vancouver. Pop: 161k+

I'm not quite understanding it either, but if I'm slightly understanding correctly: use sound wave as an ANALOGY. The half-silver mirrors allow it to "resonate" (sound terms) and ricochet off at the same time, while full silver only allows it to ricochet. (this is most likely VERY WRONG. I just now got the reasoning behind complex numbers, rotation of planes, 3d waves, etc)