Although city carriers do not work efficiently as rural carriers, they do some work and add to the USPS by "delivering", our only "Product" we actually have to sell, our "service".
Usps managers do nothing to add to our "Product", they deliver nothing. Does any office notice when a manager is on vacation? No, that's because they aren't necessary. They are similar to the lights, somewhat necessary, but only add a cost to the Usps. If we had one working employee paid a slight amount more than now to do payroll, we wouldn't need most of our managers.
Then look at the number of managers the Usps has compared to any other business. Normal businesses have 1 manager for ever 25 workers. The Usps has 40,000 managers for 640,000 workers. 640,000 employees should be able to be managed by fewer than 5,000 managers which would still be higher than our country's national average.
If the Usps was able to lay off 35,000 of their highest paid employees, not only would we be in the "Black" instead of in the red, we could, once again, make the company so profitable we could lower the national debt by $6 billion/year. When you see any Usps manager today, know that is the reason the USPS is broke.