It really pisses me off when I see this - Swollen-ego truck sped past and hopscotched others to get off the 5-S - 405-S in Valencia only to tailgate (less than car length at 70+ mph). Truck came out of nowhere to car yet and blocked rear-view of car so the only choice they would have would be to greatly exceed posted limit to see if they could move right, out of way of bully.
With a truck like that, and the way he drives, definitely compensating for something.