I also drive a semi. One time, pulling a flatbed with empty racks on it, I had a strap come loose. I pulled to the shoulder, with the 4 ways on, to retighten the strap. 2 lanes each way on this highway.
Imagine my surprise when a county sheriff deputy flies by me in the right lane, about a foot or so from where I was standing. The passing lane was wide open, not a vehicle for a mile. It really ticked me off, that the deputy wouldn't give me the same courtesy he demands from me. If I had seen the car number, that jurisdiction would have received an angry call.