Sperry nailed it on the head with what a speed trap really is. A lot of people see more than one cop in one spot and assume "SPEED TRAP!!" Just a word of advice, most cops work in pairs or groups. You usually only see one because the other one is taking notes or is writing a ticket somewhere out of the roadway. It makes it easier to chase two cars going the same speed, but the biggest reason is it makes is easier go to coffee together when you're done
I don't know how the money is distributed in Nevada for tickets, but in California, you have a fine plus a court fee. The court fee pays for the court costs. The fine itself goes straight to the county and/or city the ticket was written in. Highway patrol cops employed by the state write the most tickets and the state doesn't get any of the money for it. Their salary is paid by registration fees, which is why the Highway Patrol focuses on registration violations so much.