I was first initiated to this cultural anomaly many years ago when I was driving my little Volkswagon Bug in Texas and a big semi-truck bore down on me, flashed its lights, and literally forced me off the road. Scared the *#!!#* out of me.
Here are a few points of clarification that we've gathered so far:
- There is no expectation that anyone will slow down during these maneuvers. 70 mph is no problem.
- There are no exceptions made if, for instance, there are cars coming from the other direction - the moving over evidently allows cars to pass without concern for oncoming traffic.
- There are no markings or signs indicating that this is the customary behavior or legal use of the shoulder/right lane.
- The maneuver can be performed without the flashing lights - the slower driver simply anticipates the needs of the car behind it and drives onto the shoulder as if it is the polite thing to do. The flashing lights seem to be for the benefit of out-of-towners like me, as if to say:
"Move on over stupid, I'm comin' around!"
(One learns quickly under these circumstances.)