Traffic Violations

Riddle: There are 2 cops parked along a one-way street looking for traffic violations. They spot a taxi driver going in the wrong direction, yet they do nothing. Why?

Answer: The taxi driver wasn't driving at the time, he was walking.

Source: https://www.riddles.com/index.php/616

There are 2 cops parked along a one-way street looking for traffic violations. They spot a taxi driver going in the wrong direction, yet they do nothing.
Why? — Traffic violations by Anonymous Riddle