Here’s why officers touch the back of your car during a traffic stop

Wonder why cops touch your car when they stop you.
The second issue they mention about checking who is in back is something that happened here, as the Officer walked up (he stopped a truck with gang members) they kicked open the tailgate and shot him and he went down. They got out and he begged for his life and they shot him in the head. Later I had to transport them to court, I wanted to hurt them so bad.
https://www.clickorlando.com/traffic/2020/02/07/heres-why-officers-touch-the-back-of-your-car-during-a-traffic-stop/