Hi Steve

I do not have any good reasons why it only happens on the drivers side.
I tried to blame it on "Sven the Torquer." Someone claimed that he is a large swede with really big arms on the assembly line. He also does the engines starter bolts that are just to his right on the left side of the car.

I Think you did mentioned that you could not get the strut springs to tilt out on the left side when you replaced the struts. My right side, that I did first, swung down without any issue so I knew the left one was being weird as they should be symmetrical in clearances.
The left lower arm would not push down far enough so I loosen the rear and front nut? From that moment on I could not keep the rear one tight and it would thump over a slight bump to remind me.

Ifbinever donanother car I will study the idea of loosening the rear box from the frame and let it fall and rotate.
Why the threads are messed up might be from the manufacture or the strain from Mr. Big Arms ... Sven. Just guessing.

Enjoy your commute in the morning. That's a heck of a name for a bridge. It must be a trip in itself to get and give directions back there.
I can only guess of what other kind of words described that pot hole besides a crater. (:-)
Phil