When you fight, it requires the officer to be present and in some instances there is an added fee for his time if you lose. The 2nd event I even had my wife as a witness, but still lost. I was not guilty in either instance, but when it's only your word against patrolman, you always lose.
I'm sure you've gotten away many times speeding in the past. Just chalk this up as a life lesson. I don't speed as much as I did in my younger years, but there are occasions when I do. If I get caught, stupid me.