All games have a basic set of rules, even if that set of rules is "anything goes". On Viking MUD, we used to have a pretty loose set of rules, leaving much to the supposed common sense of the players. With the increased popularity of the Internet from 1995 and forward, however, it seemed that more detailed rules were necessary. So for us, "anything goes" is not the rule...
So what about rules for arch wizards and administrators? Well, in the MUD, we have a humoristic set of arch rules, but in practice, arch wizards are bound by their common sense, and answer only to their superiors. Administrators are equal, and (as far as the MUD is concerned) answer only to themselves and their common sense.
Why? Arch wizards and administrators sometimes have things to do which would normally conflict with the rules for mortal players or normal wizards. It would be very inconvenient if, for instance, an arch wizard couldn't wander about in open areas to check for some particular bugs.
The MUD depends on a certain level of trust between arch wizards and administrators, and when someone has been appointed to arch wizard or administrator, that is because s/he/it has earned that trust in some way. Because of that trust, in some ways, there is more tolerance between arch wizards, but also higher expectations.
What about standards for behaviour among arch wizards and administrators? This is a very difficult area, with many shades of grey. In some ways, arch wizards and administrators could be expected to overstep some boundaries others shouldn't even get close to (e.g.: privacy issues), but they shouldn't be general assholes either. If an arch wizard or an administrator crosses the line, someone higher or equal in the MUD's power hierarchy will have a talk with the person in question. That usually helps!