Does it help hiring a lawyer for a traffic offense, or will talking to the prosecutor suffice?

No attorney! You make yourself look guilty--Go to Court and present your defense or plead no contest. The Judge will consider your proof (must have proof) picture of legal mileage per hr. at a certain mile post for instance, because the ticket will say where you were ticketed. Or tell the Judge the situation, such as cop sitting by the side of the road conversing with another cop in the car behind them on their radios just waiting for you to take the off ramp and charge you with speeding so they can make their "quota" while resting off road instead of cruising the freeway like a good highway patrolman! The Judge is aware of these situations and will consider. So just tell the truth, you always do better to appear than just send in a fee.