Question

Why do police officers touch the rear of cars during traffic stops?

I've noticed that when someone gets pulled over by a police officer the police officer touches the rear of the car before making contact with driver of the car.

What's the purpose of touching the rear of the car during a traffic stop?

Answer 1

It's a tactic that police use when doing a traffic stop to prevent people from hiding illegal things in their car during a traffic stop.

Basically it's a distraction tactic. Another reason they may tap your taillight during a traffic stop is to leave their fingerprint on your car in case you take off and or do something to the officer and the car can be linked back to that officer who did the traffic stop when they dust for fingerprints on the taillight of the car.