> It would be way more annoying for LHD countries to change to RHD

As a complete aside, 1 country has done this: Sweden on 3 September 1967 and "It was by far the largest logistical event in Sweden's history"

https://en.wikipedia.org/wiki/Dagen_H

Iceland did it a year later, https://en.wikipedia.org/wiki/H-dagurinn, but since there was less then 200k people living there it was a much less dramatic change

IIRC a lot more countries did it but mostly a lot earlier (pre ww2).

Back then it would have been comparatively easy, cars were slow and there were barely any street signs etc anyway

Falkland Islands did it for a brief second, though not by choice.