D&D General A Rant: DMing is not hard.

[Maxperson]

Increased awareness of roadway threats in general, increased knowledge of traffic flow, and specific experience of how a semi maneuvers so you can anticipate their behavior on the road and what they need from you.

A semi reacts slowly and poorly, requiring you to scan far further ahead and use more advanced anticipation skills than the vast majority of 4 wheel drivers exhibit. You have a higher vantage point as well, giving you a better viewpoint to see other vehicles and how they move.

There's also some more niche skills you learn more often, like skid training and black ice training, and just learning to effectively pre-trip puts you ahead of most 4 wheel drivers.

It's certainly not impossible to pick up those skills just driving a 4 wheeler, but it's a level of awareness usually only found in other professional drivers like state troopers.

I know how traffic flows. Extremely well from decades of experience with it. Further I do anticipate their behavior already, aiding them in switching lanes and more. As for scanning further ahead, well you can do that when you're several feet higher up than a car. I already scan as far ahead as I can and am rarely surprised. Being able to see farther in a semi doesn't help me in a car. Being aware of everything around you for as far as you can see is how you avoid accidents, and I don't like being in accidents.

There's nothing there that objectively increases my ability to drive my car. There's stuff there that could increase some folks ability to drive, if they didn't already do the things you mention.

About the only thing you mention that I don't have skill with is black ice training, but it won't help me drive better because Southern California doesn't have black ice. Or any ice for that matter.