This is something that I have always wondered about. In ICI you often and almost exclusively see receptacles ground up. As the story goes it's to stop objects from sliding down an contacting the live prong of a poorly inserted plug.
The Canadian Electrical Code makes no reference to the "correct" orientation but shows the image of a receptacle ground pin up. But hot wires are supposed to be on the right bottom terminal first(I've been told). Why the discrepancy between industrial and institutional vs residential? Commercial goes either way, but if it's inherently safer ground up why are receptacles manufactured to be ground down and why is residential ground down? Over the years I've discussed this with many electricians of various backgrounds and have got a lot of different answers. Hoping to get something concrete here.