How I took it is that there's only on place on the entire planet every day where these "mediators" are. And it's only in this one place where breaking a law causes the death penalty. People do not commit crimes simply because you never know where these mediators are that day. Wesley was in the exact wrong spot at the exact wrong time.
You can unwittingly break the law (like Wesley).
So, what's the penalty in these cases if you are outside the Penalty Zone (but near a mediator)?