Reflection in the mirror. If you notice the lines on the road, plus look in the back window of the truck, on the side where the trailer numbers are, in the glass, you can see the spring that supports the air lines
There is a very short black dude driving the truck. I looked at it in photoshop and with some tweaking, a small "blob" can be seen barely above the dash horizon. Can not be any sort of caucasian individual or it would show more pronounced, or we would not even be having this discussion. But definitely and interesting photo grab and the idea the truck driver would mimic the other driver's actions in changing lanes would really make you begin to think about an "autonomous truck"
That's not an Averitt truck. All of our trucks have the company name on the airfoil and the truck number on the front of the hood on the driver's side.