But why are the doors on the left side?
As far as I can tell, this is a hang over from nautical days.
Long ago ... ships used to have their "steer board" (a long oar like device used as a rudder) on the right of the vessel which meant they docked on their left side to avoid damaging the rudder. Over time, the name steer board, shortened to sterboard then Starboard. The other side of the vessel was the porting or docking side, shortended to Port side.
Now, why the boards where put on that side, or why we endedup with green and red markers ...
JAS