I only read the original post so, I'll keep this short.
My dad was a diesel mechanic for a long time so I got to ride around in MACK trucks a lot. My favorite is the classic R model. Say..a R686ST. With the wet kit obviously. And a few times we would see idiots do this. In their little sportster cars. now obviously they are doing a eff u to the truck...Because the truck is big and in his way.
What they do not realize..it doesn't stop on a dime. the truck is slow because of torque vs. speed requirements. and sometimes you drive a 32 speed and it takes a minute to get up and going.
Ever see the gears of a transmission from a caterpillar engine from a Ford diesel truck? HUGE!!!!!
I think most intelligent drivers do actually have some understanding of how long it takes a fully loaded semi-trailer to stop compared to a car. As you say, I think it's often more of an FU to the truck driver, or it's just pure frustration at being delayed for 2 minutes. It always surprises me the things some drivers do to get where they're going 5 minutes later.
A close friend of mine drives a semi-trailer, and he recently installed one of those dash cameras. Some of the footage from it is quite unbelievable. Just completely reckless stuff; some of them don't know how close they came to being run over like a speed bump.

