IIRC, markers on the map for players were discussed at some point during the development of the RPG 3.0 script. It came to a conclusion that they should know where the places are and if they don't, they could always ask any of the available players. Having job markers on the radar will also make the radar seem cluttered up for regular players, hence the reason why it was not implemented.
I still want a command/feature where you can toggle on and off those markers however this isn't a complete solution, I know.