Generally in most MMORPGs1 the role of shopkeepers are assigned to pre-programmed NPCs. However in SAO we see Agil and Lisbeth run their own stores.
Was SAO's community-driven nature (i.e. players assume the roles as shopkeepers) a part of the original specification, or did this only occur because Kayaba trapped everyone?
1: There is one recent MMORPG I am aware of that has a player controlled economy where players have to find their own jobs within the game (i.e. farmer, blacksmith, trainer) but I can't remember the name and it is also the only MMORPG I am aware of that does this.