However in my experience, I have found that many in the industry have, in fact, scant knowledge of what happens in the next office. There have been hints of that in the series!
Whilst signing off the Virgin flight to South Africa, the presenter asked the gate operative why the entry door was always on the left hand side, to which they replied, "That's how it is, passengers on the left, cargo (catering) through the right door
I'd hazard that it came about through maritime connections, the left side being 'port' and where passengers would board
Pedants and professors feel free to correct me
SHJ