Possible reasons for such bus behavior:
5. Bus forced truck off the road (as suggested in article).
4. Bus cut in front of truck, truck could have slowed down, but stubbornly road shoulder instead.
3. Bus was using a camera based rear view mirror stolen from a Chevy Bolt that was inadvertently pointed skyward.
2. Phase II of a plot by GM to to ruin Tesla financially and keep Model 3 from coming to market.
1. Passengers on bus just couldn't wait to take a test drive.
6. The bus driver wanted to test the defensive AP safety features of "the machine that carries the machine"
4. . . . but truck stubbornly rode . . . I see this kind of thing frequently on the highway, especially at "On" ramps, as well as on city streets. People sometimes just won't take their foot off the accelerator and yield to others. Gotta drive defensively!!!!!!
The bus was in the wrong. A turn signal doesn't mean "I'm coming over so get the heck out of my way", and it doesn't give the bus the right-of-way. That said, the truck driver was an *ss for not slowing a bit and giving the bus some room to merge in. I might change my opinion if the truck driver was looking ahead, saw the traffic slowdown coming, and refused to let the bus in because it wouldn't have given him sufficient room to safely slow down.
But in the spirit of things:
6. The truck was equipped with GM's driver assist package from the Bolt, which doesn't include high-speed automatic braking.
7. The bus was being driven by Matt Kenseth, and the truck by Alex Bowman.
8. Phase of the moon, failed to calculate tide level before changing lanes
9: The bus was Elon attempting to land it on a barge
10. Bus driver was just then receiving the election results and temporarily lost all motivation to function.
11. The bus was driven by our local GM troll and was carrying a bunch of GM dealer representatives to a convention. They saw the truck carrying the Teslas and realized "if you can't beat them - destroy them".
12. The bus driver did not hear the sound of the electric cars, and mandated that the FED forces electric cars to produce more noise.
13. Bus driver distracted by new sexy glass.
Frank99, I think you got it about right. What also occurred to me is that the truck may have been driving a little too fast. The bus driver no doubt had to keep the bulk of his/her concentration forward at the slowing traffic. He/she may have glimpsed a gap in that last lane that evaporated more quickly than he/she had calculated.
14. Busload of Inter-galactic beings with no earthly lines of credit assumed a kidnap attempt was the only way to obtain much needed electric cars back home to save *their* planet.