People who work in backstabbing environments, or people who need to keep track which lie they told whom, or who to butter up in order to advance *also* get stressed and burnt out. And quite often, or so it seems to me, people who work in unfair organisations not only dole out nasty behaviour, they're at the (perceived?) receiving end of it - the promotion they did not get, the last minute workload or problem employee that gets dumped on them instead of on someone else.

I don't think that there's necessarily a causation involved in 'managers who try to be fair' and 'managers who burn out.