But the order to manage the city was clear enough and yet Parson failed because he did not understand it.
I would qualify this slightly. Parson understood the order well enough. He didn't understand the conditions behind the order which the order required. He didn't know that in order to correctly manage the city and therefore reduce the city expenses that he must "walk the rounds." It makes no sense that observing an empty bank, an empty butcher shop, an empty granary will cause them to produce more for less, so Parson didn't do it. Being the city manager must have seemed like a formality to Parson. As in "OK, I've been appointed the city manager. Great. Now I guess the city will have reduced expenses because I've got a fancy new title." He was ordered to manage the city, a task which seemed to him to have no requirements to fulfill, since things just pop in Erfworld.
How using capslock wins arguments:
So we know with 100% certainty that THIS IS HOW TRI-LINKS WORK, PERIOD END OF STORY.