How do attorneys fight traffic tickets?

In Nevada (and probably other states as well), If I get a speeding ticket for example, I am able to take it to a law firm that deals with traffic violations. I can pay usually $50—$100, and they will fight the ticket down to say a $90 parking ticket with no points on your license, and no traffic school. You simply drop off, or provide a copy of the ticket to the attorneys office, and they goto court for you.

My question is, what are they really doing? I’m sure these law offices get tons of tickets to which they represent in court and fight down. But are they really going to each case and representing you while you are not there, or is there something else that is going on? For example are they just going to the court house and dropping off a batch of speeding tickets to a judge and say “reduce these”?