[Christ]

I don't necessarily agree on the light flashing being a courtesy.

Often times, in fact, more times than not, there is no "courtesy" used to indicate a passing vehicle. Most times, the courtesy is extended by the person in the vehicle that was just overtaken, being a light flash to signal that enough space has cleared for the overtaker to re-enter the initial travel lane.

I don't think I've ever had someone give me a courtesy flash before passing. Likewise, I don't ever recall having any of those people who flashed do it in a manner that would indicate that they were attempting to overtake me in a legal manner.

Based solely on anecdotal evidence, I've been led to believe that each occurrence has been exactly the opposite. No "courtesy" involved.