With no incentive, people cease to give a shit and the service suffers.
Discussion
So the military should make more money than it costs to operate?
The military doesn't deliver the mail. And it shouldn't exist as it does either. All the military does is take and is 100x more inefficient than the postal service. Privatize that too.
It's not about making money, it's about providing a service and not being a burden. The USPS is costing too much for what they're offering. Simple as that. A lighter, quicker operation would get people their mail quicker and get statist lifers off the dole.