My last character got banned from the inn the very first time he attacked in it so I imagine that was an imm decision.
Additionally you get auto banned after triggering the bouncers a handful of times.
A number of imms have made not attacking heralds part of their religion as have a few mortal leaders and scion for a while (though that may simply have been because of muloc and eshval)
This is on top of the fact that wanted can't enter the inn, heralds have no fail boot, and bouncers make it really challenging.
Sure people get kills because people are lazy about how they act but even a barely mediocre herald who doesn't want to die is all but unkillable even by high end players.
And gear lockering is a thing as well as simply not having many targets and the fact that many race/class herald builds can be cabal enemies.