It feels automatic. Go to the airport, board the plane. It may never have occurred to you that you always board from the left hand side. And there's a reason for that. Experts say it might even date back centuries to traditional nautical custom.
Early airports were set up so that aircraft could taxi in front of the terminal and stop to discharge passengers, wrote a former US air force pilot on Quora. "It was useful for the pilot to be able to judge wing clearance from the terminal building and to put the aircraft door in front of the terminal doors. Some early transports had right-side doors into the passenger cabin, but the logic of the pilot's field of view prevailed. At some airports, stairs may be placed at forward and/or aft doors, but to avoid passengers wandering around a busy parking ramp, the loading/unloading is always on the same (almost always the aircraft's left) side. Also for safety reasons, passenger movement is kept on one side while fuelling is carried out on the other. It is also useful to unload/load baggage and cargo on the opposite side from passenger movement and the loading bridge or stairs. However, Andrew Stagg, calling himself a commercial pilot on the site, had a different take. I believe the reasoning goes back to ships, which have a port (left) and starboard (right) side. The port side was the one you would embark and disembark from, so most airplane and jetway designers followed the same convention. While most larger transport category aircraft have two front and two rear exits, the placement of catering trucks and baggage loading equipment on the right, makes using the right doors impractical." UcenterDress cocktail styled items to wear of the wedding