You have already stated that it's okay to cross to the left of oncoming traffic at a signal-controlled-intersection. Given this, you already have allowed that "driving on the right side" is not appropriate 100% of the time. Therefore, you personally drive to the left multiple times a day.What does this even mean? I need more of an explanation because this does not only make no sense... it also has no bearing on the conversation at hand.
This point has already been made above more than a few times in this discussion by several other people.
A median crossover is just another intersection, but without a signal and usually without lines marking where to stay. Notably, quite a few controlled intersections do NOT have lines indicating where to cross, but everyone still stays to the left in those controlled intersections even without lines to so instruct them. Therefore, for many people (other than you obviously) there is a habit pattern and an expectation that staying to the left of an opposing vehicle is the right way to drive in an intersection, whether or not a traffic signal exists. I get it, you don't agree. But you should recognize that there is precedent for driving "on the left" that you encounter every single day.
This will probably blow your mind:
N.C. Department of Transportation's information about why diverging diamond interchanges on highways help safely move motorists in high traffic areas