In most the USA, or at least Arizona, you have to serve someone. Just dropping something in a mail box doesn't mean dick. The very people that invented the traffic cameras up in Scottsdale were caught dodging the process servers from triggers from their own camera.

Another words, you have to spend hundreds of dollars chasing someone down, by the time you add that on to how easy it is to jam up the ticket in court by demanding an actual human being accuse you, it's not the easy win some may think. You're basically looking at $500+ to try and prosecute someone for a $300 ticket.