That empty dump truck looks empty so it weighs approximately 25,000 lbs. Here's the thing. It's not whether the driver can tell if the difference between a 10,000 lbs. and 13,000 lbs. load when he drives his truck away from a site. It's the fact that the load instantaneously increased by more than 3,000 lbs. It's actually more than that, when you consider the car was sideways (wheels effectively locked) and was being pushed up a hill.
I can notice the difference when I load my summer wheels/tires into my car to get them switched over. Especially when going up hills.