Some may know that I'm very hawkish about truck blind spots and the right or left hook collision dangers they present.
But here's another difference between hitting a truck/trailer vs. a car. You may want to do an experiment, in which case you'll need a parked car (preferably one who's owner won't complain about a minor scratch, and a parked truck trailer.
This is a try this at home experiment, just be very careful. Some may prefer to run it in their imaginations only.
Riding slowly, approach a parked at a shallow angle simulating it starting a right hook across your path. At the moment just before collision reach out, fend off, and recover. You can also do this using your shoulder or upper body to check you into a parallel course. With practice you can develop this checking or fending maneuver into something you can execute at high speed, (bike polo teaches it well), and the skill can save you from crashing if right hooked by a car.
Now approach the middle of a truck trailer and try the same maneuver (SLOWLY). See, there's nothing to fend off against. Th trailer is at shoulder or head height and will clothesline you, most likely allowing the bicycle to slip underneath. If the trailer were moving forward, this would lead to being crushed under the rear axle.
I suspect that this tendency to slide under the high body trucks is a major contributor to the high mortality rate of truck right hook accidents. Even at low speed it's hard to avoid sliding under to be crushed.